Quantum reserves the right to make changes and improvements to its products, without incurring
any obligation to incorporate such changes or improvements in units previously sold or shipped.
Quantum reserves the right to make changes to this product manual without incurring any
obligation to notify recipients of earlier versions of the product manual.
You can request Quantum publications from your Quantum Sales Representative or order them
directly from Quantum.
Publication Number: 81-60043-04, November 10, 2003
SERVICE CENTERS
Quantum Service Center Quantum Asia-Pacific Pte. Ltd. Quantum Customer Service
715 Sycamore Avenue 50 Tagore Lane #b1-04 Quantum Ireland, Ltd.
Milpitas, California 95035 Singapore, 2678 Finnabair Industrial Park
Phone (888) 827-3378 Phone: (65) 450-9333 Dundalk
FAX: (800) 4DISKFAX FAX: (65) 452-2544 County Louth, Ireland
BBS: (800) 472-9799 Phone: (353) 42-55350
Fax: (353) 45-55355
Copyright 1995-2001 by Quantum Corporation. All rights reserved. Printed in U.S.A.
Quantum and the Quantum logo are trademarks of Quantum Corporation, registered in the U.S.A.
and other countries. DLTtape and the DLTtape logo are trademarks of Quantum Corporation.
Products mentioned herein are for identification purposes only and may be trademarks or
registered trademarks of their respective companies.
USER MANUAL STATEMENTS FOR CLASS A EQUIPMENT (INTEGRATIBLE TAPE SYSTEM)
This equipment generates, uses, and may emit radio frequency energy. The equipment has been
type tested and found to comply with the limits for a Class A digital device pursuant to Part 15 of
FCC rules, which are designed to provide reasonable protection against such radio frequency
interference.
Operation of this equipment in a residential area may cause interference in which case the user at
his own expense will be required to take whatever measures may be required to correct the
interference.
Any modifications to this device - unless expressly approved by the manufacturer - can void the
user’s authority to operate this equipment under part 15 of the FCC rules.
Note: Additional information on the need to interconnect the device with shielded (data) cables or
the need for special devices, such as ferrite beads on cables, is required if such means of interference
suppression was used in the qualification test for the device. This information will vary from device
to device and needs to be obtained from the EMC group or product manager.
Warning!
This is a Class A product. In a domestic environment this product may cause radio interference in
which case the user may be required to take adequate measures.
Achtung!
Dieses ist ein Gerät der Funkstörgrenzwertklasse A. In Wohnbereichen können bei Betrieb dieses
Gerätes Rundfunkstörungen auftreten, in welchen Fällen der Benutzer für entsprechende
Gegenmaßnahmen verantwortlich ist.
Warning!
This Class A digital apparatus complies with Canadian ICES-003.
Cet appareil numérique de la classe A est conforme à la norme NMB-003 du Canada.
Attention!
Ceci est un produit de Classe A. Dans un environnement domestique, ce produit risque de créer des
interférences radioélectriques, il appartiendra alors à l'utilisateur de prendre les mesures spécifiques
appropriées.
USER MANUAL STATEMENTS FOR CLASS A EQUIPMENT (continued)
USER MANUAL STATEMENTS FOR CLASS B EQUIPMENT (TABLETOP VERSION)
This equipment has been tested and found to comply with the limits for a Class B digital device,
pursuant to Part 15 of the FCC rules. These limits are designed to provide reasonable protection
against harmful interference in a residential installation. Any modifications to this device unless expressly approved by the manufacturer - can void the user’s authority to operate this
equipment under part 15 of the FCC rules. Operation is subject to the following two conditions:
(1) This device may not cause harmful interference and (2) This device must accept any
interference that may cause undesirable operation.
This equipment generates, uses, and can radiate radio frequency energy and, if not installed
and used in accordance with the instructions, may cause harmful interference to radio
communications. However, there is no guarantee that interference will not occur in a particular
installation. If this equipment does cause harmful interference to radio or television reception,
which can be determined by turning the equipment off and on, the user is encouraged to try to
correct the interference by one or more of the following measures:
• Reorient or relocate the receiving antenna.
• Increase the separation between the equipment and receiver.
• Connect the equipment into an outlet on a circuit different from that to which the receiver is
connected
•Consult the dealer or an experienced radio/TV technician for help.
Note: Additional information on the need to interconnect the device with shielded (data) cables
or the need for special devices, such as ferrite beads on cables, is required if such means of
interference suppression was used in the qualification test for the device. This information will
vary from device to device and needs to be obtained from the EMC group or product manager.
This Class B digital apparatus complies with Canadian ICES-003.
Cet appareil numérique de la classe B est conforme à la norme NMB-003 du Canada.
USER MANUAL STATEMENTS FOR CLASS B EQUIPMENT (continued)
Table D-2. When to Use a Cleaning Tape Cartridge ................................................. D-12
xviiiQuantum DLT 4000 Tape Drive
REVISION HISTORY
This Revision History provides a concise publications record of this manual. It lists the manual’s
revision levels, release dates, and a summary of changes for each release.
Manual Number
- Revision Level
81-108336-01May 5, 1995Original issue
81-108336-02Caution added for unloading a tape cartridge
81- 60043- 01March 10, 1996
Date of ReleaseSummary of Changes
Part number 81-108336-02 obsoleted
Manual-wide, trademark copyrights, and other changes.
Fast Data Transfer Rate correction.
Figure 2-1 and 3-6 corrected.
Section E added to POST testing.
Table 3-2 corrected.
Description of tape cartridge corrected.
Notes added to Loading a Cartridge section.
Added a caution to Unloading a Cartridge section.
Chapter 4 rewritten.
POST description updated.
Figure 5-2 updated, page 5-6.
Table 5-1 updated, page 5-11.
Table 5-2 updated, page 5-14.
Table 7-1 added, page 7-4.
Table 7-1 consolidated, page 7-8.
Caution message added, page 7-9.
Table 8-1 modified, page 8-8.
Table 8-2 modified, page 8-15.
Table 8-6 modified, page 8-21.
Product Family description and table added, page 8-22.
Density Code updated, page 8-49.
Table 8-3, additions and modifications, pages 8-65 and 8-67.
Tables A-1, A-5, A-8, A-9, A-10, A-12, A-14, A-16, A-17, A-20,
and A30 changed (pages A-3, A-1, A-13, A-14, A-15, A-17, A-18,
A-23).
Quantum DLT 4000 Tape Drive
xix
Revision History
Manual Number
- Revision Level
81-60043-02 April 08, 1999 Entire manual rewritten to conform to corporate standard for product
81-60043-03 September 18, 2000 Revised.
81-60043-04 April 4, 2001 Updated corporate address and reader comment address.
81-60043-04 A02 November 10, 2003 Changed Service Center contact number from (800) 826-8022 to
Date of Release Summary of Changes
manuals. Manual updated to include new version of the DLT4000
tape drive (Chapters 1 and 2); SCSI command updates (Chapter 5);
consolidation of Request Sense ASC/ASCQ codes into one complete
table (Chapter 5) and tape cartridge additions (Appendix D).
Chapter 2: Pinout tables corrected for 50-pin single-ended and
differential SCSI connector signals (Tables 2-2 and 2-3).
Chapter 5: Corrections made to LOG SENSE command’s DEVICE
STATUS page (Log Parameter Format and TSD, ClnQ, and ClnR bits).
Appendix A: Changed field descriptions in Table A-2.
(888) 827-3378 per ECO C008218.
xx
Quantum DLT 4000 Tape Drive
ABOUT THIS MANUAL
“About this Manual” outlines the scope and contents of this manual. It contains information about
the intended audience, purpose of the manual, document organization, and document conventions.
AUDIENCE
This manual is written for original equipment manufacturers (OEMs) that are
integrating the Quantum DLT4000 tape drive and into a system or subsystem.
Its primary audience is the OEM technical staff that makes tape drive purchase
and configuration decisions, and system integrators that are responsible for the
SCSI interface. Additionally, the manual can be used by technically astute endusers for installation and operation of the tape drive, although that is a
secondary audience.
PURPOSE
This manual describes the rackmount and tabletop versions of the DLT 4000
tape drive. It is intended to provide the information necessary to integrate the
tape drive into a computer system or subsystem.
DOCUMENT ORGANIZATION
This product manual contains five chapters, a number of appendixes of related
useful information, and an index. It includes an overview of the Small Computer
System Interface (SCSI) and detailed descriptions of the messages and SCSI
commands as used by the tape drive. The manual is organized as follows:
Chapter 1General Description and Specifications
This chapter contains a brief description of and specifications for the
drive.
Quantum DLT 4000 Tape Drivexxi
About This Manual
Chapter 2Hardware Implementation
This chapter contains configuration and installation information for the
tape drive, descriptions of the drive controls and LEDs, and information
on running the self-test.
Chapter 3SCSI Description
This chapter provides a detailed description of the logical interfaces of
the tape drive. It describes the products’ compliance with the ANSI
SCSI-2 specification. The drive’s many optional features are described
here and throughout the manual.
Chapter 4Messages
This chapter provides a list and description of most messages supported
by the tape drive. The SCSI message system allows communication
between SCSI initiators and SCSI targets (the tape drive, in this case)
for interface management and for command elaboration and
qualification.
Chapter 5SCSI Commands
This chapter describes in detail each command supported by the tape
drive. The SCSI command system enables an initiator to direct a tape
drive to perform a wide range of operational and diagnostic functions.
This chapter also provides sense key information for the REQUEST
SENSE SCSI command.
Appendix ADefinition of Vendor Unique Sense Data Information
Appendix A provides a list of internal status codes related to the
REQUEST SENSE SCSI command.
Appendix BEEPROM-Resident Bugcheck and Event Logs
Appendix B provides an explanation of the error and event logs stored in
semi-permanent, non-volatile memory.
Appendix CUpdating the Firmware
Appendix C provides a step-by-step procedure for updating a tape drive’s
PCBA controller-resident firmware.
Quantum DLT 4000 Tape Drivexxii
About This Manual
Appendix DThe Tape Cartridge
Appendix D provides tape cartridge handling and inspection procedures,
information on the write-protect switch, how to load and unload a tape
cartridge, and how to use a cleaning tape cartridge.
CONVENTIONS
This manual uses the following conventions to designate specific elements:
ElementConventionExample
CommandsUppercase (unless case-sensitive)FORMAT UNIT
MessagesUppercaseINVALID PRODUCT NUMBER
Hexadecimal NotationNumber followed by lowercase h25h
Binary NotationNumber followed by lowercase b101b
Decimal NotationNumber without suffix512
AcronymsUppercasePOST
AbbreviationsLowercase, except where standard
usage requires uppercase
READER COMMENTS
Quantum is committed to providing the best products and service. Our manuals
are important components of our products. We encourage your comments,
suggestions, and corrections for this manual. Please send all comments to:
Quantum Technical Publications
4001 Discovery Drive, Suite 1100
Boulder, CO 80303
Quantum DLT 4000 Tape Drivexxiii
Mb (megabits)
MB (megabytes)
About This Manual
Quantum DLT 4000 Tape Drivexxiv
Chapter 1
GENERAL DESCRIPTION AND SPECIFICATIONS
This chapter provides a description and gives specifications for the Quantum DLT™4000 Tape Drive.
1.1PRODUCT DESCRIPTION
The Quantum DLT 4000 tape drive is a high-performance, high-capacity,
streaming cartridge tape product designed for efficient data back-up for midrange
and high-end computing systems. With Quantum’s DLT advanced linear
recording technology and a precision tape guide system, the drive is ideally
suited for high-end workstation, server, and network backup requirements.
Using data compression, the DLT 4000 tape drive features a formatted capacity
of 40.0 GB* and a sustained user data transfer rate of 3.0 MB/second* (native
capacity is 20.0 GB; native data transfer rate is 1.5 MB/second).
The device is an extended-length, 5.25-inch form factor, half-inch cartridge tape
drive. The design includes a two-channel read/write head, Lempel-Ziv (LZ)
high-efficiency data compression, and tape mark directory to maximize data
throughput and minimize data access time.
The tape drive is available in rackmount (Figure 1-1) or tabletop (Figure 1-2)
form. The tabletop versions of the drive are packaged in a housing that includes
its own cooling fan and power supply, requiring ac power.
The following subsections contain full specifications for the Quantum DLT 4000
tape drive. Specifications for the DLTtape tape media cartridges are also
included.
1.3.1 Physical Specifications
The following table provides physical dimensions for the DLT 4000.
General Description and Specifications
Table 1–1 DLT 4000 Physical Dimensions
DimensionRackmountTabletop
(Version 1)
Height3.25 in. (8.26 cm) without front
bezel; 3.40 in (8.64 cm) with front
bezel.
Width5.70 in. (14.48 cm) behind front
bezel; 5.84 in (14.83 cm) with front
bezel.
Depth9.00 in. (22.86 cm) measured from
back of front bezel; 9.60 in. (24.38
cm) including front bezel
Typical Weight:6 lb., 7 oz (2.9 kg)(14 lb., 9 oz) 6.63 kg
Note: Mounting hole pattern for the bottom and sides of the drive is industry standard.
5.77 in.
(14.66 cm)
9.25 in.
(23.50 cm)
13.08 in.
(33.22 cm)
Tabletop
(Version 2)
4.88 in.
(12.40 cm)
9.06 in.
(23.01 cm)
12.60 in.
(32.00 cm)
Quantum DLT 4000 Tape Drive1-3
General Description and Specifications
1.3.2 Interface Type
DLT 4000 tape drives are available with narrow SCSI-2 fast single-ended or
differential high voltage interfaces.
1.3.3Storage Capacity
The following table provides the ranges of capacity (native and compressed) for
the tape drive, depending on which DLTtape cartridge is used.
Table 1–2 DLT 4000 Storage Capacity
DLTtape Cartridge
(Length of Medium)
DLTtape IV
(extended 1780 foot tape)
DLTtape IIIxt
(extended 1780 foot tape)
DLTtape III
(standard 1167 foot tape)
Note: A compression factor of 2:1 can be attained, depending on the data type and
subject to the limitations of the SCSI bus design and the configuration of the
system in which the tape drive is installed.
Native
Storage Capacity
20.0 GB User Data
15.0 GB User Data
10.0 GB User Data
Compressed
Storage Capacity
40.0 GB User Data
(compressed 2:1)
30.0 GB User Data
(compressed 2:1)
20.0 GB User Data
(compressed 2:1)
1.3.4 Performance Data
The following table provides performance data for the DLT 4000 tape drive.
Table 1–3DLT 4000 Performance Data
FeatureDescription
Transfer Rate, User Native
Transfer Rate, Raw Native
Transfer Rate, Compressed *
Error RatesRecoverable READ Error Rate = 1 in 1x107
* = Depending on data type and SCSI bus limitations/system configuration.
Note that data is typical; times may be longer if error recovery time is needed.
1.5 MB/second 2.5
MB/second More
than 3.0 MB/second maximum write, 10 MBburst
mode; More than 2.5 MB/second maximum read, 10
MBburst mode
Recoverable WRITE Error Rate = 1 in 1x10
Uncorrected Error Rate = 1 in 1x1017 bits read
Undetected Error Rate = 1 in 1x1027 bits read
6
1-4Quantum DLT 4000 Tape Drive
General Description and Specifications
Table 1–3DLT 4000 Performance Data (continued)
FeatureDescription
Tracks128; 64 pairs
Linear Bit Density81,600 bpi per track
READ / WRITE Tape Speed98 inches/second
Rewind Tape Speed150 inches/second
Linear Search Tape Speed150 inches/second
Average Rewind Time70 seconds
Maximum Rewind Time140 seconds
Average Access Time (from BOT)45 seconds
Maximum Access Time (from BOT)90 seconds
Load to BOT (typical)48 seconds - previously written (slightly longer if using
a blank tape)
Load to BOT (max time using V120
firmware or greater)
Unload from BOT17 seconds
Nominal Tape Tension3.0 +/- 1 oz when stationary; 4.7
* = Depending on data type and SCSI bus limitations/system configuration
Note that data is typical; times may be longer if error recovery time is needed.
5.2 minutes with blank tape that fails calibration (time
includes calibration retries)
+/- 1 oz at operating speed
1.3.5Environmental Specifications
The following table lists operating and non-operating environmental
specifications for the DLT 4000 tape drive.
Table 1–4 DLT 4000 Environmental Specifications
SpecificationOperating LimitsNon-Operating Limits
(Power On; No Tape Loaded)
Wet Bulb Temperature25°C (77°F)25°C (77°F)
Dry Bulb Temperature
Range
Temperature Gradient11°C (52°F) /hour (across range)15°C (59°F) /hour (across range)
Temperature Shock10°C (50°F) (over two minutes)15°C (59°F) (over two minutes)
Relative Humidity20 to 80% (noncondensing)10 to 95% (noncondensing)
Humidity Gradient10% / hour10% / hour
10°C to 40°C (50°F to 104°F)-40°C to 66°C (-40°F to 151°F)
5 to 10 Hz
10 to 50 Hz
50 to 200 Hz
Each of the X, Y, and Z axes for one hour (3 hours total)
1.3.6Power Requirements
The following table provides the applicable power requirements for rackmount
and tabletop versions of the DLT 4000 tape drive. Note that the tabletop DLT
4000 requires ac power.
Table 1–7 DLT 4000 Power Requirements
Requirement Rackmount Tabletop
Electrical Rating (Auto Ranging)Not Applicable100 to 240 VAC
Power Requirements25 W, steady state;
27 W, maximum
Power Consumption:
+5 V (±5%) bus *2.0 A, steady state;
2.5 A, maximum
+12 V (±5%) bus *0.8 A, steady state;
1.5 A, maximum
* = Voltage measured at the power bus connector pins.
The rackmount version of the drive complies with FCC Class A in a standard
enclosure; the tabletop version complies with the FCC Class B limits.
Quantum DLT 4000 Tape Drive1-7
General Description and Specifications
1.3.8EMI and Safety Certifications
Table 1−8 provides the certifications held by the rackmount and tabletop
versions of the tape drive. Table 1−9 provides the safety certification held by the
tape drives.
Table 1–8 EMI Emission Certificates
RackmountTabletop
CEmark Class A
VCCi Class 1
CISPR 22 Class A
FCC Class A Devices
Table 1–9Safety Certifications
Rackmount and Tabletop
UL CSA
TÜV “BG”
MARK IEC
CEmark Class B
VCCi Class 2
CISPR 22 Class B
FCC Class B Devices
1.3.9Reliability (Projected)
Mean time between failures (MTBF) for the tape drive is projected to be 200,000
hours at 100% duty cycle. Head life is 10,000 tape motion hours.
Media durability is projected to be 1,000,000 passes of the tape medium across
the read/write heads (15,000 uses).
Quantum Corporation does not warrant that predicted MTBF is representative
of any particular unit installed for customer use. Actual figures vary from unit
to unit.
1-8Quantum DLT 4000 Tape Drive
General Description and Specifications
1.3.10 Acoustic Noise Emissions
The following tables provide the tape drive’s acoustic noise emission levels, both
as noise power and sound pressure. Information about acoustic emissions is also
provided in German to fulfill an international requirement.
Acoustics – Preliminary declared values per ISO9296 and ISO 7779/EN27779
Noise Power Emission LevelSound Pressure Level(LNPEc)(LPAc)ProductIdleStreamingIdleStreamingRackmountNot applicableNot applicableNot applicableNot applicableTabletop4.6 B5.1 B30.0 dB41.0 dB[Current values for specific configurations are available from Quantum representatives.
1B = 10 dBA.]
Table 1-11 Acoustic Noise Emissions for German Noise Declaration Law
Schallemissionswerte - VorläufigeWerteangaben nach ISO 9296 und ISO
7779/DIN EN27779:
SchalleistungspegelSchalldruckpegel LwAd, BLpAm, dBA (Zuschauerpositionen)GerfdtLeeraufBetriebLeeraufBetriebRackmountN/A5,5 BN/A45,0 BTabletop5,2 B5,3 B39,0 dB40,0 dB[Aktuelle Werte für spezielle Ausrüstungsstufen sind über die Quantum Equipment
Vertretungen erhältlich. 1 B = 10 dBA]
1.3.11 Tape Drive Recording Type
The tape drive uses 2 - 7 RLL code with DLT 2000, DLT 2000xt, or DLT 4000
formats; MFM with 2.6 GB / 6.0 GB DLT 260 and DLT 600 formats.
Quantum DLT 4000 Tape Drive1-9
General Description and Specifications
1.3.12 DLTtape Recording Media Specifications
The following table provides specifications for tape media.
Table 1-12 DLTtape Media Specifications
DLTtape
Media Type
DLTtape IIIWidth: 0.5 in., metal particle
DLTtape IIIxtWidth: 0.5 in., metal particle
DLTtape IVWidth: 0.5 in., metal particle
Specifications
Length: 1200 feet (standard 1167 ft. tape)
Cartridge Dimensions: 4.1 in x 4.1 in x 1.0 in
Shelf Life: 30 years min. @ 20°C & 40% RH (non-condensing)
Usage: 1,000,000 passes (typical office/computer environment)
Length: 1800 feet (extended 1780 ft tape)
Cartridge Dimensions: 4.1 in x 4.1 in x 1.0 in
Shelf Life: 30 years min. @ 20°C & 40% RH (non-condensing)
Usage: 1,000,000 passes (typical office/computer environment)
Length: 1800 feet (extended 1780 ft. tape)
Cartridge Dimensions: 4.1 in x 4.1 in x 1.0 in
Shelf Life: 30 years min. @ 20°C & 40% RH (non-condensing)
Usage: 1,000,000 passes (typical office/computer environment)
1-10Quantum DLT 4000 Tape Drive
Chapter 2
HARDWARE IMPLEMENTATION
This chapter describes how to install the internal tape drive or “brick” into a rackmount system. This
includes configuration jumper settings, connector pin assignments, installation instructions, power
and signal cabling descriptions, and operating instructions. This chapter also includes information
on configuring and connecting the tabletop version of the drive into a system.
This chapter covers the following topics:
• Safety, Handling and Electrostatic Discharge (ESD) Protection (Section 2.1)
describes appropriate guidelines when working with the tape drive.
• Drive Setup (Section 2.2) describes how to set up the tape drive for SCSI ID,
TERMPWR, and parity checking.
•Drive Installation (Section 2.3) describes how to mount and install the tape
drive into the system.
•Drive Connections (Section 2.4) identifies the connectors on the tape drive
including the SCSI, power and optional loader connectors.
the front panel controls and LED’s and describes their functionality. It also
explains density selection.
• Power On Self Test (POST) (Section 2.6) describes the activities that occur
when power is first applied to the drive.
• Troubleshooting (Section 2.7) lists troubleshooting tips in the event that the
tape drive fails.
2.1 SAFETY, HANDLING AND ELECTROSTATIC DISCHARGE (ESD) PROTECTION
Inappropriate or careless handling of tape drives may result in damage to the
product. Follow the precautions and directions to prevent damaging the tape
drive.
Quantum DLT 4000 Tape Drive2-1
Hardware Implementation
2.1.1 Safety Precautions
For your safety, follow all safety procedures described here and in other sections of
the manual.
• Remove power from the computer system (or expansion unit) before
installing or removing the tape drive to prevent the possibility of electrical
shock or damage to the tape drive. Unplug the unit that contains or is to
contain the drive from ac power to provide an added measure of safety.
• Read, understand, and observe any and all label warnings.
2.1.2Handling
Damage to the drive can occur as the result of careless handling, vibration, shock,
or electrostatic discharge (ESD). Always handle the tape drive with care to avoid
damage to the precision internal components.
Follow these guidelines to avoid damage to the drive:
• Always observe prescribed ESD precautions.
• Keep the drive in its anti-static bag until ready to install.
• Always use a properly fitted wrist strap or other suitable ESD protection
when handling the drive.
• Hold drive only by its sides. Do not touch any components on the PCBA.
• Always handle the drive carefully and gently. A drop of ¼ inch onto a bench
or desktop may damage a drive.
• Do not bump, jar, or drop the drive. Use care when transporting the drive.
• Always gently place the drive flat, PCB side down, on an appropriate ESD-
protected work surface to avoid the drive being accidentally knocked over.
• Do not pack other materials with the drive in its anti-static bag.
• Place the drive in the anti-static bag before placing it in a shipping
container.
• Do not stack objects on the drive.
• Do not expose the drive to moisture.
• Do not place hands or foreign objects inside the tape drive’s door/receiver
area.
2-2Quantum DLT 4000 Tape Drive
Hardware Implementation
2.1.3Electrostatic Discharge (ESD) Protection
Various electrical components on/within the tape drives are sensitive to static
electricity and Electrostatic Discharge (ESD). Even a static buildup or discharge
that is too slight to feel can be sufficient to destroy or degrade a component's
operation.
To minimize the possibility of ESD-related damage to the drive, we strongly
recommend using both a properly installed workstation anti-static mat and a
properly installed ESD wrist strap. When correctly installed, these devices reduce
the buildup of static electricity that might harm the drive.
Observe the following precautions to avoid ESD-related problems:
• Use a properly installed anti-static pad on your work surface.
• Always use a properly fitted and grounded wrist strap or other suitable ESD
protection when handling the drive and observe proper ESD grounding
techniques.
• Hold the drive only by its sides. Do not touch any components on the
PCBA.
• Leave the drive in its anti-static bag until you are ready to install it in the
system.
• Place the drive on a properly grounded anti-static work surface pad when it
is out of its protective anti-static bag.
• Do not use the bag as a substitute for the work surface anti-static pad. The
outside of the bag may not have the same anti-static properties as the
inside. It could actually increase the possibility of ESD problems.
• Do not use any test equipment to check components on the PCBA. There are
no user-serviceable components on the drive.
2.2DRIVE SETUP
Drive setup for DLT 4000 tape drive includes the following:
• Set the SCSI ID for the drive (default = SCSI ID 5)
• Configure the drive to provide TERMPWR
• Set parity checking for the drive (default = parity checking enabled)
If you want to change any of the settings, go to the applicable subsection;
otherwise, proceed directly to section 2.3.
Quantum DLT 4000 Tape Drive2-3
Hardware Implementation
129
2.2.1 Set the Rackmount Drive SCSI ID
Each device on the SCSI bus must have a unique SCSI ID address assigned to it.
For specific recommendations for assigning SCSI IDs, refer to the system or SCSI
controller documentation.
Rackmount drives can be configured for SCSI ID addresses that range from 0 to 7
(default=5) in one of two ways:
a) jumper the 10-pin SCSI ID jumper block shown in Figure 2-1, or
b) set the IDs through firmware. If the firmware is set to SCSI ID = 5, then no
jumpers are installed on the SCSI ID jumper block.
This subsection discusses setting the SCSI ID on the rackmount drive via the
jumper block. Table 2-1 lists the SCSI ID address and jumper settings.
NOTES
The default setting for the tape drive is SCSI ID 5; the host adapter is
typically SCSI ID 7.
A jumper must be installed across Pins 9-10 (Remote ID Present pins)
for the host to recognize any SCSI ID selections from this jumper
block.
SCSI ID Jumper Block (J13)
10
(default SCSI ID 5 shown)
Figure 2-1 DLT 4000 SCSI ID Jumper Location (Rackmount Version Shown)
2-4Quantum DLT 4000 Tape Drive
Front Panel
Loader Connector (J12)
Hardware Implementation
Table 2-1 SCSI ID Address Selections
SCSI IDJumper Across Pins:
9-107-85-63-41-2
010000
110001
210010
310011
410100
5 (default)10101
610110
710111
0 = No Jumper installed1 = Jumper installed
Quantum DLT 4000 Tape Drive2-5
Hardware Implementation
1
1
252617
18
2.2.2 Configure the Rackmount Drive for TERMPWR (Single-Ended Only)
A SCSI bus must be terminated at each end of the bus. At least one device must
supply terminator power (TERMPWR). Quantum recommends that every device
on the SCSI bus be configured to supply TERMPWR to ensure that there is a
sufficient level of voltage along the SCSI bus.
Install a jumper across Pins 3 and 4 (Figure 2-2) to enable TERMPWR.
Front Panel
ALDR (J26)
TERMPWR (J24)
Not used
Parity Check (J25)
2
Install Jumper on Pins 3-4
to enable TERMPWR.
Install Jumper on Pins 1-2
to disable Parity Checking.
2.2.3 Configure The Rackmount Drive for Parity Checking
The default setting for DLT 4000 tape drives is to have parity checking enabled.
If the system to which you are configuring the rackmount tape drive does not
generate SCSI parity, there are two ways that parity checking can be disabled.
You can disable parity checking by:
(a) Installing a jumper across Pins 1 and 2 on the parity check connector as
shown in Figure 2-2, or
(b) Installing a jumper across Pins 7 and 8 on the SCSI ID jumper block shown
in Figure 2-1.
2.2.4 Configure the Tabletop Drive
Figures 2-3 and 2-4 show the locations of the controls for the tabletop versions of
the drive. Note that these drives are normally configured to meet customer
specifications before they leave the factory so should not require any internal
configuration changes on-site.
Figure 2–3 Tabletop (Version 1) Back Panel Controls
Quantum DLT 4000 Tape Drive2-7
SCSI ID Pushbutton
Hardware Implementation
SCSI Signal
Connector (IN)
SCSI ID Pushbutton
Power Switch
SCSI Signal Connector
(Out/Termination)
Figure 2–4 Tabletop (Version 2) Back Panel Controls
SCSI ID - The SCSI ID default for the tabletop drive is set to 5; the drive can be
configured for SCSI ID addresses that range from 0 to 7 using the SCSI ID
pushbutton. Press the button above or below the ID number display to set the
desired SCSI ID. The top button increases the ID number; the bottom button
decreases the ID number.
TERMPWR and/or Parity Check - The tabletop version of the drive can be
internally configured to supply TERMPWR or parity checking. Contact your
service representative if you want to change either of these settings on the
tabletop version of the drive.
2.3DRIVE INSTALLATION
This section describes how to mount and secure the drive in the system. Figure 2–
5 shows the mounting locations and dimensions for the drive.
Power Connector
2-8Quantum DLT 4000 Tape Drive
9.60 (24.38)
9.00 (22.86)
Hardware Implementation
3.25
(8.26)
0.82
(2.08)
5.70
(14.48)
5.50
(13.97)
3.13
(7.94)
Side View - Inches (Centimeters)
9.60 (24.38)
1.88
(4.76)
3.40
(8.64)
Front Panel
5.84
(14.83)
0.10
(0.25)
3.13
(7.94)
Bottom View - Inches (Centimeters)
1.88
(4.78)
Figure 2–5 Rackmount Drive Mounting Locations – Side and Bottom Views
Quantum DLT 4000 Tape Drive2-9
Front Panel
Hardware Implementation
DLT 8000 Library
Drive Side
In some systems, it may be more convenient to connect the SCSI bus and power
cables to the drive before securing it in the system.
Because of the variety of mounting possibilities for tape drive, the instructions
presented here are general in nature. They should be used only as a guide for
mounting the drive in your system.
Mount the drive in the system by performing the following steps:
1.Position the drive in the system and align the drive mounting holes (side or
bottom) with those in the system.
2.Using four (4) screws, secure the tape drive in its bay or chassis. Note that
screws used to mount the tape drive must be 8 x 6-32 UNC-2B screws. There
is no danger of these screws touching electronic components or otherwise
damaging the tape drive.
2.4DRIVE CONNECTIONS
The following warning applies to the bezel connector located under the front panel
of the tape drive. This connector is an internal connector so is not discussed in
detail in this manual.
WARNING
The bezel connector pinout on the DLT 4000 tape drive (Model
TH5XB-NP) is not compatible with any other DLT products. A flex
cable adapter is available to connect these tape drives to a
library/loader system that uses header pins for the bezel connection.
Do not use this flex cable adapter to connect to drives other than
the Model TH5XB-NP. The following label has been applied to the
drive to warn the user when making this connection:
WARNING
°
DLT 4000
DLT 7000 Library
2-10Quantum DLT 4000 Tape Drive
Hardware Implementation
Pin 1
Pin 1
Drive Back
The three external connectors on the DLT 4000 tape drive that are discussed in
this manual are the SCSI, power and optional loader connectors. Tabletop
connectors are described in subsection 2.4.3.
2.4.1 SCSI and Power Connectors (Rackmount)
Figure 2-6 shows the pin orientation for the 50-pin SCSI connector and 4-pin
power connector located on the back of the tape drive. Pin assignments for the
single-ended and differential SCSI connectors are listed in Tables 2–2 and 2-3; pin
assignments for the power connector are listed in Table 2-4.
Align the appropriate SCSI and power cables to their matching connectors.
Carefully connect the cables, to avoid bending or damaging the connector pins.
Optional Power
Connector
SCSI-2 Connector
4-Pin Power Connector
(Not used)
Figure 2-6 SCSI and Power Cable Connectors (Rackmount Version Shown)
Quantum DLT 4000 Tape Drive2-11
Hardware Implementation
Table 2–2 Single-Ended SCSI Pin Assignment
Signal NamePin NumberPin NumberSignal Name
Ground12-DB(0)
Ground34-DB(1)
Ground56-DB(2)
Ground78-DB(3)
Ground910-DB(4)
Ground1112-DB(5)
Ground1314-DB(6)
Ground1516-DB(7)
Ground1718-DB(P)
Ground1920Ground
Ground2122Ground
Reserved2324Reserved
Open2526TERMPWR
Reserved2728Reserved
Ground2930Ground
Ground3132-ATN
Ground3334Ground
Ground3536-BSY
Ground3738-ACK
Ground3940-RST
Ground4142-MSG
Ground4344-SEL
Ground4546-C/D
Ground4748-REQ
Ground4950-I/O
Note: The minus sign (-) next to a signal indicates active low.
2-12Quantum DLT 4000 Tape Drive
Hardware Implementation
Table 2–3 Differential SCSI Pin Assignment
Signal NamePin NumberPin NumberSignal Name
Open12Ground
DB(0)34-DB(0)
DB(1)56-DB(1)
DB(2)78-DB(2)
DB(3)910-DB(3)
DB(4)1112-DB(4)
DB(5)1314-DB(5)
DB(6)1516-DB(6)
DB(7)1718-DB(7)
DB(P)1920-DB(P)
DIFFSENS2122Ground
Ground2324Ground
TERMPWR2526TERMPWR
Ground2728Ground
ATN2930-ATN
Ground3132Ground
BSY3334-BSY
ACK3536-ACK
RST3738-RST
MSG3940-MSG
SEL4142-SEL
C/D4344-C/D
REQ4546-REQ
I/O4748-i/O
Ground4950Ground
Quantum DLT 4000 Tape Drive2-13
Hardware Implementation
Table 2–4 4-Pin Power Connector Pin Assignment
Pin NumberSignal Name
1+12 VDC
2Ground (+12 V return)
3Ground (+5 V return)
4+5 VDC
2.4.2 Optional Loader Connector (Rackmount)
The loader connector provides signals to be used when the tape drive is part of a
loader/library configuration. Figure 2-7 shows the location of the connector.
Front Panel
SCSI ID Jumper Block (J13)
Figure 2–7 Loader Connector Block Location (Rackmount Version Shown)
2-14Quantum DLT 4000 Tape Drive
10-Pin Loader Connector (J12)
Hardware Implementation
2.4.3 Tabletop Drive Connectors
Figures 2-8 and 2-9 show the locations of the connectors for the tabletop version
of the drive.
SCSI ID Pushbutton
Figure 2–8 Tabletop (Version 1) Back Panel Connectors
Quantum DLT 4000 Tape Drive2-15
Hardware Implementation
SCSI Signal
Connector (IN)
SCSI ID Pushbutton
Power Switch
SCSI Signal Connector
(Out/Termination)
Figure 2–9 Tabletop (Version 2) Back Panel Connectors
Align the appropriate SCSI and power cables to their matching connectors.
Carefully connect the cables and avoid bending or damaging the connector pins.
1. Make sure the power switch is in the off (0) position.
2. Connect one end of the SCSI cable to the SCSI IN connector on the back
panel of the drive. Connect the other end of the SCSI cable to the SCSI
connector on your system, or for daisy-chained configurations, to another
SCSI device.
3. Snap the wire cable clamps into place to secure the cables.
4. Be sure to terminate the SCSI bus. If the tabletop drive is the last or only
device on the bus, terminate the bus by connecting the SCSI terminator to
the SCSI OUT connector on the back of the drive. Depending on the
terminator supplied, snap the wire cable clamps into place or tighten the
screws to secure the terminator.
If the tabletop drive is not the last or only device on the bus, install a
terminator on the last device on the SCSI bus.
5. Connect one end of the power cord to the power connector on the back of the
drive. Connect the other end of the cord to the ac outlet.
Power Connector
2-16Quantum DLT 4000 Tape Drive
2.5 DRIVE CONTROLS AND LIGHT EMITTING DIODES (LEDS)
Density Override LED
This section identifies the front panel controls and LED’s and describes their
functionality. It also explains density selection.
2.5.1 Front Panel Controls and LED’s
This section describes the front panel controls and Light Emitting Diodes
(LED’s) used to operate the tape drive; all controls and LED’s are located on the
tape drive’s front panel. Figure 2-10 shows the locations of the controls and
LED’s on the front panel.
In addition to the controls and LED’s, the tape drive also has an audible beeper
that signals when the drive’s cartridge insert/release handle can be safely used.
Use these controls and LED’s to operate the tape drive and monitor the tape
drive’s activities.
Density LED’s
2.6
6.0
10.0/15.0
20.0
Hardware Implementation
Write-Protected LED
Tape In Use LED
Compress LED
Density Select Button
Use Cleaning Tape LED
Operate Handle LED
Unload Button
Cartridge Insert/Release
Figure 2-10 DLT 4000 Front Panel
Quantum DLT 4000 Tape Drive2-17
Hardware Implementation
Table 2–5 LED Functionality
LEDLED ColorDescription
Density -
2.6, 6.0,
10.0/15.0, 20.0
CompressAmberOn = Compression mode enabled (compression only valid for
Density OverrideAmberOn = Operator selected a density from the density Select
Write-ProtectedOrangeOn = Tape is Write-Protected
Tape In UseAmberIrregular Blinking = Tape is moving; the drive is calibrating,
AmberRefer to Table 2-6 and subsection 2.5.2.
10, 15, or 20 GB densities only).
Off = Compression mode disabled.
Blinking = Compress mode manually overridden by operator.
Button on the front panel.
Off = Density to be selected by the host (automatic).
Refer to subsection 2.5.2 for Density Select information.
Off = Tape is Write-Enabled
reading, writing, or rewinding the tape.
Regular Blinking = The tape is loading, unloading, or
rewinding.
On = A cartridge is loaded in the tape drive, but the tape is not
moving; the drive is ready for use. This may also mean no
application is communicating with the tape drive’s controller,
or that the application is communicating but is not delivering
any command that impact tape motion.
2-18Quantum DLT 4000 Tape Drive
Hardware Implementation
Use Cleaning
Tape
AmberOn = Tape drive needs cleaning or tape is bad.
Remains on after cleaning tape unloads = Cleaning tape
attempted to clean the drive head, but the tape expired so
cleaning was not done.
After cleaning, LED lights again when (data) tape cartridge is
reloaded = Problem tape cartridge. Try another cartridge. If
problem persists, contact service representative.
Off = Cleaning is complete or cleaning is unnecessary.
Appendix D has more information on cleaning tape usage.
Quantum DLT 4000 Tape Drive2-19
Hardware Implementation
Table 2–5 LED Functionality (continued)
LEDLED ColorDescription
Operate HandleGreenOn = Insert/Release handle can be operated.
Off = Do not operate Insert/Release handle.
Blinking = Close the Insert/Release handle and wait for
Operate Handle LED to light steadily.
Table 2–6 Density LED Functionality
Density LED
(Amber)
2.6On = Tape is recorded in 2.6 GB format.
6.0On = Tape is recorded in 6.0 GB format.
10.0 / 15.0On = Tape is recorded in 10.0 GB (DLTtape III cartridge) / 15.0 GB (DLTtape
20.0On = Tape is recorded in 20.0 GB (DLTtape IV cartridge) format.
Note that these LED’s operate only if the correct media is loaded in the drive. For example,
the default density of a DLTtape IV cartridge is 20.0 GB; if you are using a DLTtape IV
cartridge, the density must be set to 20.0 GB. If you set the density to a different setting, the
LED’s do not light and the density function does not work properly.
Description
Blinking = Tape is being forced by operator to record in this density; 2.6 GB
has been selected for a WRITE from BOT.
Blinking = Tape is being forced by operator to record in this density; 6.0 GB
has been selected for a WRITE from BOT.
IIIxt cartridge) format.
Blinking = Tape is being forced by operator to record in this density, 10.0
GB / 15.0 GB has been selected for a WRITE from BOT.
Blinking = Tape is being forced by operator to record in this density, 20.0 GB
has been selected for a WRITE from BOT.
2-20Quantum DLT 4000 Tape Drive
Hardware Implementation
Table 2-7 Control Functionality
ControlDescription
Density Select ButtonRefer to subsection 2.5.2.
Unload ButtonUse the Unload button to unload the tape cartridge. When you
push the Unload button, the tape drive waits until any active
writing of data to tape is completed, then begins its unload
sequence.
The tape drive rewinds the tape medium back into the cartridge.
The tape must be completely rewound and unloaded into the
cartridge before the cartridge can be removed from the tape drive.
A complete unload operation may take 17 seconds from Beginning
of Tape (BOT).
Note that if the tape drive is in an error state (all LED’s on the righthand side of the front panel are flashing), pushing the Unload
button causes the tape drive to reset and unload the tape, if
possible. The Operate Handle LED will be lit steady if this is
possible.
Cartridge Insert/Release
Handle
Audible BeeperA beeper sound indicates that the cartridge insert/release handle
Use the Cartridge Insert/Release Handle to load or eject a tape
cartridge only when the tape drive’s Operate Handle LED is lit and
after the beeper sounds its tone. Lift the handle to its open
position, or lower it to its closed position.
can be safely operated. When the drive emits its single beep tone,
verify that the green Operate Handle LED is lit steadily before
opening the handle.
CAUTION: To prevent damage to the tape drive, never operate the
insert/release handle unless the green Operate Handle LED is lit and
you have heard the beep tone that signals that the tape drive’s
handle can be opened.
Quantum DLT 4000 Tape Drive2-21
Hardware Implementation
2.5.2Selecting Density
This subsection describes the drive’s density select features.
CAUTION
If a prerecorded tape is reused and a WRITE from the beginning of
tape (BOT) executes (No Append Write), any data already recorded
on the tape will be lost. This includes density changes, since they
occur only when writing from BOT.
NOTES
On all READ and all WRITE APPEND operations, the data density that
already exists on the tape cartridge remains the density.
Default density of a DLTtapeTM III cartridge is 10.0 GB, native. The
only optional selections for DLTtape III cartridges are 2.6 GB, 6.0 GB,
10.0 GB (compression OFF), or 20.0 GB (compression ON).
Default density of a DLTtape IIIxt cartridge is 15.0 GB, native
(compression OFF), or 30.0 GB (compression ON). No other density is
supported.
Default density of a DLTtape IV cartridge is 20.0 GB, native
(compression OFF). A density of 40.0 GB is user-selectable. No other
density is supported.
When writing from BOT, tape density may be changed by:
• Using the Density Select Button on the front panel of the tape drive. Using
the Density Select Button always overrides density selection via the host.
• Using the operating system to issue a density designation. In this case, the
amber Density Override LED on the tape drive’s front panel turns off,
indicating an automatic or host density selection.
• Native default density for the DLTtape IV is 20.0 GB. The only available
option is compression on or off.
2-22Quantum DLT 4000 Tape Drive
Hardware Implementation
Selecting Density on the Tape Drive
To select density on the tape drive:
1. Load the tape cartridge into the tape drive. The amber Tape in Use LED
blinks while the tape loads and calibrates.
2. After calibration is complete, the Tape In Use LED remains steadily lit. The
appropriate tape density LED along the left edge of the drive’s front panel
lights to indicate the tape’s prerecorded density (if any), such as 2.6 GB or
6.0 GB.
3. Use the tape drive’s density Select Button to select the desired density, if
different than that indicated by the lighted tape density LED. Density
selection is inactive until a WRITE from BOT is issued. The controller
retains the selected density until 1) the density selection is changed, or 2)
the tape is unloaded.
Selecting Density via the Host over the SCSI Bus
1. Use the SCSI MODE SELECT command to indicate the desired density
(Chapter 5).
2. Write data to the tape from BOT.
For Example:
A user loads a tape cartridge previously recorded at 2.6 GB density. The user then
presses the Density Select button to select 10.0 GB density. The following events
take place:
• The amber 2.6 LED remains lit – the density has not yet changed and the
steadily lit LED reflects the tape’s recorded density.
• The amber 10.0 LED blinks – this signals that a density change is pending.
• The amber Density Override LED lights.
When a WRITE from BOT occurs:
• The amber 2.6 LED turns off
• The amber 10.0/15.0 LED lights steadily
• The amber Density Override LED remains lit
Table 2-8 explains the activity of LED’s during density selection.
Quantum DLT 4000 Tape Drive2-23
Hardware Implementation
Table 2–8 LED Activity During Density Selection
If…Then…
The density Select Button
is not used
The density Select Button
is used and the actual
tape density is the same
as the density selected
via the button
The density Select Button
is used and the actual
tape density differs from
the density selected via
the button
The lighted LED’s show the actual density when the tape is
being read from and written to. The LED’s light steadily;
Density Override LED remains off.
The LED’s that reflect the actual density and the Density
Override both are lit. For example, if the actual density is
10.0 GB and 10.0 GB is selected via the Select Button, the
LED next to “10.0” lights.
The LED that reflects the actual density lights steadily. The
LED that reflects the SELECTED density blinks. The Density
Override lights steadily.
For example, if the actual tape density is 10.0 GB and the
selected density is 6.0 GB, the 10.0 LED lights steadily, the
6.0 LED blinks, and the Density Override LED lights steadily.
2.6POWER ON SELF TEST (POST)
When power is applied to the tape drive, the drive performs a POST. POST
completes in about 15 seconds and the tape drive should respond normally to all
commands; POST is complete after Stage 2 in Table 2-9. However, it might take
longer for the media to become ready.
After a bus reset, the tape drive responds within a bus selection time-out period
(per the ANSI SCSI specification).
The following table lists the sequence of events:
2-24Quantum DLT 4000 Tape Drive
Hardware Implementation
Table 2–9 POST/Media Ready Activity
StageActivity
1The LED’s along the right-hand side of the front panel light in sequence from
top to bottom. All LED’s remain lit for a few seconds.
2The LED’s along the left-hand side of the front panel light together for about
three seconds, then turn off. POST is complete after this stage.
3The green Operate Handle, orange Write Protected, and amber User Cleaning
Tape LED’s turn off. The amber Tape in Use LED blinks while the tape drive
initializes.
4Following initialization, the tape drive is in one of the states described in Table
2-10. Upon completion, the POST is successful. If the POST is not successful,
refer to Section 2.8 Troubleshooting.
Table 2–10 Tape Drive States Following Initialization
StateLED Display and Activity
A tape cartridge is present and
the handle is down.
No tape cartridge present.The Tape in Use LED = Off. The Operate Handle LED = On.
A tape cartridge is present, but
the handle is up (not
recommended).
The tape drive detects an error
condition.
The drive is powered on with
the handle in open position.
The tape drive loads the medium from the cartridge. The
Tape In Use LED stops blinking and remains on. The LED next
to the tape’s actual density is on. When the Density Override
LED blinks, a density may be selected. The tape drive is ready
for use and the media is positioned at BOT.
Insert/Release Handle is unlatched. Tape drive beeper sounds
tone to signal that the handle may be raised and a tape
cartridge inserted.
The Tape In Use LED = Off. The Operate Handle LED flashes.
When the Insert/Release Handle is lowered, the cartridge
loads. If handle will not lower, ensure the tape cartridge is
pushed all the way into the tape drive.
Right- or left-hand LED’s blink repeatedly. Try to unload the
tape and reinitialize the tape drive by pressing the Unload
button or turn the drive power off then back on. The LED’s
stop blinking and the drive attempts to reinitialize. Note that
after pressing the Unload button you may have to wait five
minutes before the Operate Handle LED lights due to the
retry. The LED’s light steadily, then turn off if the test
succeeds.
Operate Handle LED is blinking. Close the Insert/Release
Handle and wait for LED to light steadily.
Quantum DLT 4000 Tape Drive2-25
Hardware Implementation
2.7 TROUBLESHOOTING
Table 2-11 lists troubleshooting tips in the event that your tape drive fails its
power-on self test or if it signals a problem via its front panel LED’s.
If, after attempting the recommended actions listed in Table 2-11, the problem still
exists or recurs, a hardware failure may be the cause. Contact your service
representative.
Table 2–11 Troubleshooting Chart
If…Then…You Should…
System does not
recognize the tape
drive.
System may not be
configured to recognize the
SCSI ID.
SCSI ID may not be uniqueChange the SCSI ID and reconfigure the
Configure system to recognize the tape
drive’s ID.
system. The new ID becomes effective at
the next power on.
SCSI adapter parameters may
not be correct
SCSI signal cable may be looseEnsure SCSI cable is fully seated at each
SCSI terminator may be loose
or not present on the bus
SCSI bus may not be
terminated correctly
SCSI terminator may not be at
end of bus or more than two
terminators may be present.
SCSI bus may be too long.
Too many devices on the bus.
Check SCSI adapter documentation.
connector end.
Ensure correct, secure termination of
bus.
If tape drive is last or only device on bus
(except for adapter), make sure
terminator is installed on tape drive.
If tape drive is not the last or only device
on the bus, check the cable connections
and ensure that the bus is properly
terminated at each end.
Ensure that a terminator is installed at
each end of the bus. One terminator is
usually installed at the host end of the
bus.
Limit bus length to ANSI SCSI standard
for the SCSI interface being used.
Limit the number of devices on the bus
(including the SCSI adapter) to match the
limits of the interface being used.
2-26Quantum DLT 4000 Tape Drive
Hardware Implementation
Table 2–11 Troubleshooting Chart (Continued)
If…Then…You Should…
System does not
recognize the tape
drive (cont.)
The tape drive does
not power up.
All LED’s on the right
or on the left side of
the tape drive front
panel are blinking.
When loading a tape
cartridge, the LED’s on
the right side of the
tape drive front panel
are blinking.
A device may not have been
turned on and a valid SCSI ID
may not have been
configured prior to the system
powering on and loading
BIOS.
No power is reaching the tape
drive.
A drive fault has occurred.If a tape was loaded, try to unload the
The tape drive has detected a
possible drive leader problem.
Turn drives power on first, and then turn
on power to the system. Do this so that
the drive is properly recognized by the
system.
Check the tape drive’s power cable
connection at the rear of the drive.
tape and reinitialize the drive by pressing
the Unload button, or by turning power
to the drive off then back on. The LED’s
stop blinking as the drive attempts to
reinitialize. The LED’s light steadily again,
then extinguish if the test succeeds. Be
sure to isolate the tape that was loaded
in the drive and perform the TapeCartridge Inspection Procedure described
in appendix D.2.
Isolate the tape cartridge from all other
tape devices; not doing so may damage
another tape device. Perform the TapeCartridge Inspection Procedure described
in appendix D.2 on the tape cartridge.
Contact your service representative.
Nonfatal or fatal errors
occur for which the
cause cannot be
determined.
SCSI bus termination or the
SCSI bus cable connections
may be incorrect.
The ac power source
grounding may be incorrect
(tabletop version).
Quantum DLT 4000 Tape Drive2-27
Ensure the SCSI bus is terminated and
that all connections are secure.
Use
an ac outlet for the tabletop tape unit on
the same ac line used by the host system.
Hardware Implementation
2-28Quantum DLT 4000 Tape Drive
Chapter 3
SCSI DESCRIPTION
This chapter provides a detailed description of the logical interfaces of the tape drive. The drive is
fully compliant with the ANSI SCSI-2 standard for tape drive devices and implements many optional
features.
3.1SCSI OVERVIEW
The Small Computer System Interface (SCSI) is a specification for a peripheral
bus and command set that is an ANSI standard. The standard defines an I/O
bus that supports up to eight devices (narrow SCSI).
ANSI defines three primary objectives of SCSI-2:
1. To provide host computers with device-independence within a class of
devices
2. To be backward-compatible with SCSI-1 devices that support bus parity
and that meet conformance level 2 of SCSI-1
3. To move device-dependent intelligence to the SCSI-2 devices
Important features of SCSI-2 implementation include the following:
• Efficient peer-to-peer I/O bus with up to 16 devices
• Asynchronous transfer rates that depend only on device implementation
and cable length
• Logical addressing for all data blocks (rather than physical addressing)
• Multiple initiators and multiple targets
• Distributed arbitration (bus contention logic)
• Command set enhancement
3.2SCSI COMMANDS
ANSI classifies SCSI commands as mandatory, optional, or vendor-specific. The
mandatory and optional commands implemented for the drives are summarized
in Table 3–1 and described fully in Chapter 5, SCSI Commands.
Quantum DLT 4000 Tape Drive3-1
SCSI Description
Table 3–1 Implemented ANSI SCSI-2 Commands
CommandCodeClassDescription
Erase19hMandatoryCauses all of the tape medium to be
erased, beginning at the current position
on the logical unit.
INQUIRY12hMandatoryRequests that drive information be sent
to the initiator. The initiator may also
request additional information about
the drive.
LOAD UNLOAD1BhOptionalRequests that the target enable or
disable the logical unit for further
operations. Prior to performing the load
unload, the target ensures that all data,
filemarks, and/or setmarks shall have
transferred to the tape medium.
LOCATE2BhOptionalCauses the target to position the logical
unit to the specified block address in a
specified partition. When complete, the
logical position is before the specified
position. Prior to performing the load
unload, the target ensures that all data,
filemarks, and/or setmarks shall have
transferred to the tape medium.
LOG SELECT4ChOptionalProvides a means for the initiator to
manage statistical information
maintained by the drive about the drive.
This standard defines the format of the
log pages but does not define the exact
conditions and events that are logged.
LOG SENSE4DhOptionalProvides a means for the initiator to
retrieve statistical information
maintained by the drive about the drive.
SPACE11hMandatoryProvides a selection of positioning
functions (both forward and backward)
that are determined by the code and
count.
TEST UNIT READY00hMandatoryProvides a means to check if the logical
unit is ready.
VERIFY2FhOptionalRequests the drive to verify the data
written to the medium.
WRITE0AhOptionalRequests the drive to write the data
transferred from the initiator to the
medium.
WRITE BUFFER3BhOptionalUsed in conjunction with the READ
BUFFER command as a diagnostic for
testing target memory and the integrity
of the SCSI bus.
Used to update drive firmware from the
host via the SCSI bus.
WRITE FILEMARKS10hMandatoryRequests that the target write the
specified number of filemarks or
setmarks to the current position on the
logical unit.
3.3SIGNAL STATES
The following paragraphs describe signal values and SCSI ID bits.
3.3.1 Signal Values
All signal values are actively driven true (low voltage). Because the signal
drivers are OR-tied, the bus terminator’s bias circuitry pulls false when it is
released by the drivers at every SCSI device. If any device asserts a signal, (e.g.,
OR-tied signals), the signal is true. Table 3–2 shows the ANSI-specified and
defined signal sources. Any device can assert RST at any time.
3-4Quantum DLT 4000 Tape Drive
Table 3–2 Signal Sources
Signals
SCSI Description
Bus PhaseBSYSELC/D I/O
MSG REQ
BUS FREENoneNoneNoneNoneNoneNone
ARBITRATIONAllWinnerNoneNoneS IDS ID
SELECTIONI&TInitNoneInitInitInit
RESELECTIONI&TTargTargInitTargTarg
COMMANDTargNoneTargInitInitNone
DATA INTargNoneTargInitTargTarg
DATA OUTTargNoneTargInitInitInit
STATUSTargNoneTargInitTargNone
MESSAGE INTargNoneTargInitTargNone
MESSAGE OUTTargNoneTargInitInitNone
All:The signal is driven by all SCSI devices that are actively arbitrating.
SCSI ID: Each SCSI device that is actively arbitrating asserts its unique SCSI ID bit. The other
seven (or fifteen) data bits are released. The parity bit DB (P or P1) can be released or
driven true, but is never driven false during this phase.
I&T:The signal is driven by the initiator, drive, or both, as specified in the SELECTION and
RESELECTION phase.
ACK ATNDB(7–0)
DB(P)
DB(15-8)
DB(P1)
Init:If driven, this signal is driven only by the active initiator.
None:The signal is released; that is, not driven by any SCSI device. The bias circuitry of the bus
terminators pulls the signal to the false state.
Winner: The signal is driven by the winning SCSI device.
Targ: If the signal is driven, it is driven only by the active drive.
Quantum DLT 4000 Tape Drive3-5
SCSI Description
3.3.2 SCSI ID Bits
SCSI permits a maximum of eight SCSI devices on a SCSI bus (16 devices are
permitted when using wide SCSI). Each SCSI device has a unique SCSI ID
assigned to it. This SCSI ID provides an address for identifying the device on the
bus. On the drive, the SCSI ID is assigned by configuring jumpers or connecting
remote switches to the option connector. Chapter 2, Hardware Implementation
has full instructions for setting the SCSI ID.
3.4SCSI SIGNALS
The following paragraphs define SCSI signals and bus timing values.
3.4.1 SCSI Signal Definitions
Table 3–3 defines the SCSI bus signals.
Table 3–3 SCSI-2 Bus Signal Definitions
SignalDefinition
ACK
(acknowledge)
ATN (attention)A signal driven by an initiator to indicate that it has a message to send.
BSY (busy)An OR-tied signal that indicates that the bus is in use.
C/D
(control/data)
DB(7–0,P)
(data bus)
A signal driven by the initiator as an acknowledgment of receipt of
data from a target or as a signal to a target indicating when the target
should read the data (out) lines.
A signal driven by a target that indicates whether CONTROL or DATA
information is on the DATA BUS. True (low voltage) indicates
CONTROL.
Eight data-bit signals, plus a parity-bit signal that form a DATA BUS.
DB(7) is the most significant bit and has the highest priority (8 or 16bit) during ARBITRATION. Bit number, significance, and priority
decrease downward to DB(0). A data bit is defined as 1 when the
signal value is true (low voltage) and 0 when the signal value is false
(high voltage). Data parity DB(P) is odd. Parity is undefined during
ARBITRATION.
3-6Quantum DLT 4000 Tape Drive
Table 3–3 SCSI-2 Bus Signal Definitions (continued)
SignalDefinition
SCSI Description
DB(15–8,P1)
(data bus)
I/O
(input/output)
MSG (message)A signal driven by a target during the MESSAGE phase.
REQ (request)A signal driven by a target to indicate a request for an information
RST (reset)
SEL (select)
Eight data-bit signals, plus one parity-bit signal, that forms an
extension to the DATA BUS. They are used for 16-bit (wide) interfaces.
DB(15) is the most significant bit and has the higher priority (but
below bit DB(0) during ARBITRATION. Bit number, significance, and
priority decrease downward to DB(8). Data Parity DB (P1) is odd.
A signal driven by a target that controls the direction of data
movement on the DATA BUS with respect to an initiator. True indicates
input to the initiator.
Also used to distinguish between SELECTION and RESELECTION modes.
transfer to or from the initiator. Each byte of data transferred is
accompanied with a REQ/ACK “handshake”. See also, ACK.
An OR-tied signal that initiates a RESET condition.
An OR-tied signal used by an initiator to select a target or by a target to
reselect an initiator.
3.4.2 Signal Bus Timing
The ANSI SCSI-2 standard defines the SCSI bus timing values shown in Table
3–4.
Quantum DLT 4000 Tape Drive3-7
SCSI Description
Timing DescriptionValueDescription
Arbitration Delay2.4 µsMinimum time a SCSI device waits from asserting BSY
Assertion Period90 nsMinimum time a drive asserts REQ while using
Bus Clear Delay800 nsMaximum time for a SCSI device to stop driving all
Table 3–4 SCSI Bus Timing Values
for arbitration until the DATA BUS can be examined to
see if arbitration has been won; there is no maximum
time.
synchronous data transfers; also, the minimum time
that an initiator asserts ACK while using synchronous
data transfers.
bus signals after:
1. BUS FREE is detected.
2. SEL is received from another SCSI device during
ARBITRATION.
3. Transition of RST to true.
For condition 1, the maximum time for a SCSI device
to clear the bus is 1200 ns (1.2 µs) from BSY and SEL
first becoming both false.
If a SCSI device requires more than a bus settle delay
to detect BUS FREE, it clears the bus within a bus clear
delay minus the excess time.
Bus Free Delay800 nsMaximum time a SCSI device waits from its detection
of BUS FREE until its assertion of BSY when going to
ARBITRATION.
Bus Set Delay1.8 µsMaximum time for a device to assert BSY and its SCSI
ID bit on the DATA BUS after it detects BUS FREE to
enter ARBITRATION.
Bus Settle Delay400 nsMinimum time to wait for the bus to settle after
changing certain control signals as called out in the
protocol definitions.
Cable Skew Delay10 nsMaximum difference in propagation time allowed
between any two SCSI bus signals measured between
any two SCSI devices.
1
Recommended Time.
3-8Quantum DLT 4000 Tape Drive
SCSI Description
Table 3–4 SCSI Bus Timing Values (continued)
Timing DescriptionValueDescription
Data Release Delay400 nsMaximum time for an initiator to release the DATA
BUS signals following the transition of the I/O signal
from false to true.
Deskew Delay45 nsMinimum time required to wait for all signals
(especially data signals) to stabilize at their correct,
final value after changing.
Disconnection Delay200 µsMinimum time that a drive waits after releasing BSY
before participating in an ARBITRATION when
honoring a DISCONNECT message from the initiator.
Hold Time45 nsMinimum time added between the assertion of REQ
or ACK and changing the data lines to provide hold
time in the initiator or drive while using standard
(slow) synchronous data transfers.
Negation Period90 nsMinimum time that a drive negates REQ while using
synchronous data transfers; also, the minimum time
Power-On to
Selection
10 s
than an initiator negates ACK while using
synchronous data transfers.
1
Recommended maximum time from power
application until a drive is able to respond with
appropriate status and sense data to the TEST UNIT
READY, INQUIRY, and REQUEST SENSE commands.
1
Reset to Selection
Time
250
ms
Recommended maximum time after a hard RESET
1
condition until a drive is able to respond with
appropriate status and sense data to the TEST UNIT
READY, INQUIRY, and REQUEST SENSE commands.
Reset Hold Time25 µsMinimum time for which RST is asserted; there is no
maximum time.
Selection Abort Time200 µsMaximum time that a drive (or initiator) takes from its
most recent detection of being selected (or
reselected) until asserting a BSY response.
1
Recommended Time.
Quantum DLT 4000 Tape Drive3-9
SCSI Description
Timing DescriptionValueDescription
Table 3–4 SCSI Bus Timing Values (continued)
Selection Time-Out
Delay
Transfer Period
(set during an SDTR
message.)
1
Recommended Time.
3.5SCSI BUS PHASES
The SCSI architecture includes eight distinct phases:
1. BUS FREE phase
2. ARBITRATION phase
3. SELECTION phase
4. RESELECTION phase
5. COMMAND phase
6. DATA phases (In/Out)
250
ms
Recommended minimum time a SCSI device should
1
wait for a BSY response during SELECTION or
RESELECTION before starting the time-out procedure.
Minimum time allowed between the leading edges of
successive REQ pulses and of successive ACK pulses
while using standard or fast synchronous data
transfers. The period range is 200 to 500ns minimum,
standard, or 100 to 500ns minimum, fastsynchronous.
7. STATUS phase
8. MESSAGE phases (In/Out)
The last four phases are called the “information transfer phases”.
The SCSI bus can never be in more than one phase at any given time. In the
following descriptions, signals that are not mentioned are not asserted.
3.5.1 BUS FREE Phase
The BUS FREE phase indicates that there is no current I/O process and that the
SCSI bus is available for a connection.
SCSI devices detect the BUS FREE phase after the SEL and BSY signals are
both false for at least one bus settle delay.
3-10Quantum DLT 4000 Tape Drive
SCSI Description
During normal operation, the BUS FREE phase is entered when the drive
releases the BSY signal. However, the BUS FREE phase can be entered following
the release of the SEL signal after a SELECTION or RESELECTION phase timeout. BUS FREE might be entered unexpectedly. If, for example, an internal
hardware or firmware fault makes it unsafe for the tape drive to continue
operation without a full reset (similar to a power-up reset), or if ATN is asserted
or a bus parity error is detected during non-tape data transfers.
CAUTION
Any occurrence of a bus parity error (i.e., a single-bit error) should
be considered serious: it implies the possibility of undetected
double-bit error may exist on the bus. This may cause undetected
data corruption. On properly configured SCSI buses, parity errors
are extremely rare. If any are detected they should be addressed by
improving the configuration of the SCSI bus. A well-configured SCSI
bus in a normal environment should be virtually free of bus parity
errors.
Bus parity errors cause the tape drive to retry the operation, go to
the STATUS phase, or go to BUS FREE and prepare Sense Data.
Retrying of parity errors during Data Out Phase when writing is
normally not done, but can be enabled by changing the
EnaParErrRetry parameter in the VU EEROM Mode Page. This feature
is not enabled by default because of possible negative impact on
device performance (the data stream on writes cannot be pipelined
as well).
Initiators normally do not expect the BUS FREE phase to begin because of the
drive’s release of the BSY signal unless it has occurred after the detection of a
reset condition or after a drive has successfully transmitted or received one of
the following messages:
Messages Transmitted from Drive:
• DISCONNECT
• COMMAND COMPLETE
Quantum DLT 4000 Tape Drive3-11
SCSI Description
Messages Received by Drive:
• ABORT
• BUS DEVICE RESET
• RELEASE RECOVERY
If an initiator detects the release of the BSY signal by the drive at any other
time, the drive is indicating an error condition to the initiator. The drive can
perform this transition to the BUS FREE phase independently of the state of the
ATN signal. The initiator manages this condition as an unsuccessful I/O
process termination. The drive terminates the I/O process by clearing all pending
data and status information for the affected nexus. The drive can optionally
prepare sense data that can be retrieved by a REQUEST SENSE command.
Bus Free Sequence
1. BSY and SEL signals are continuously false for one bus settle delay.
2. SCSI devices release all SCSI bus signals within one bus clear delay.
If a SCSI device requires more than one bus settle delay to detect the BUS FREE
phase, then it releases all SCSI bus signals within one bus clear delay minus the
excess time to detect the BUS FREE phase.
The total time to clear the SCSI bus cannot exceed one bus settle delay plus one
bus clear delay.
3.5.2 ARBITRATION Phase
The ARBITRATION phase allows one SCSI device to gain control of the SCSI
bus so that it can initiate or resume an I/O process.
The SCSI device arbitrates for the SCSI bus by asserting both the BSY signal
and its own SCSI ID after a BUS FREE phase occurs.
Arbitration Sequence
1. The SCSI device waits for the BUS FREE phase to occur.
2. The SCSI device waits a minimum of one bus free delay after detection of the
BUS FREE phase before driving any signal.
3. The SCSI device arbitrates for the SCSI bus by asserting the BSY signal and
its SCSI ID.
3-12Quantum DLT 4000 Tape Drive
SCSI Description
4. The SCSI device waits at least an arbitration delay to determine arbitration
results.
NOTE
Step 4 requires that every device complete the arbitration phase to
the point of SEL being asserted (for a SELECTION or RESELECTION
phase) to avoid hanging the bus.
• If a higher priority SCSI ID bit is true on the DATA BUS, the SCSI
device loses the arbitration.
• The losing SCSI device releases the BSY signal and its SCSI ID bit
within one bus clear delay after the SEL signal asserted by the
arbitration winner becomes true.
• The losing SCSI device waits for the SEL signal to become true
before releasing the BSY signal and SCSI ID bit when arbitration is
lost.
• The losing SCSI device returns to Step 1.
• If no higher priority SCSI ID bit is true on the DATA BUS, the SCSI
device wins the arbitration and asserts the SEL signal.
• The winning SCSI device waits at least one bus clear delay plus one
bus settle delay after asserting the SEL signal before changing any
signals.
3.5.3 SELECTION Phase
The SELECTION phase allows an initiator to select a drive to initiate a drive
function.
The SCSI device that won the arbitration has both the BSY and SEL signals
asserted and has delayed at least one bus clear delay plus one bus settle delay
before ending the ARBITRATION phase. The SCSI device that won the
arbitration becomes an initiator by not asserting the I/O signal.
During SELECTION, the I/O signal is negated so that this phase can be
distinguished from the RESELECTION phase.
Quantum DLT 4000 Tape Drive3-13
SCSI Description
3.5.3.1 Selection Sequence
The initiator:
1. Sets the DATA BUS to the OR of its SCSI ID bit and the drive’s SCSI ID
bit.
2. Asserts the ATN signal (signaling that a MESSAGE OUT phase is to follow
the SELECTION phase).
3. Waits at least two deskew delays.
4. Releases the BSY signal.
5. Waits at least one bus settle delay.
6. Looks for a response from the drive.
The drive:
7. Determines that it is selected when the SEL signal and its SCSI ID bit are
true and the BSY and I/O signals are false for at least one bus settle delay.
8. Can examine the DATA BUS to determine the SCSI ID of the selecting
initiator.
9. Asserts the BSY signal within a selection abort time of its most recent
detection of being selected (this is required for correct operation of the
selection time-out procedure).
The drive does not respond to a selection if bad parity is detected. Also, if more
than two SCSI ID bits are on the DATA BUS, the drive does not respond to
selection.
Note that the initiator will release the SEL signal and may change the DATA
BUS no less than two deskew delays after it detects that the BSY signal is true.
The drive waits until the SEL signal is false before asserting the REQ signal to
enter an information transfer phase. Other signals (e.g., MSG, C/D) may also
be asserted.
3.5.3.2 Selection Time-Out
Two optional time-out procedures are specified for clearing the SCSI bus if the
initiator waits a minimum of a selection time-out delay and there has been no
BSY signal response from the drive.
3-14Quantum DLT 4000 Tape Drive
The initiator asserts the RST signal.
1. The initiator follows these steps:
a) Continues asserting the SEL and ATN signals and releases the DATA
BUS.
b) If it has not detected the BSY signal to be true after at least a selection
abort time plus two deskew delays, the drive releases the SEL and ATN
signals, allowing the SCSI bus to go to the BUS FREE phase.
When responding to selection, SCSI devices ensure that the selection was still
valid within a selection abort time of their assertion of the BSY signal. Failure
to comply with the requirement could result in an improper selection.
3.5.4 RESELECTION Phase
RESELECTION is an optional phase that allows a drive to reconnect to an
initiator to continue an operation that was previously started by the initiator
but was suspended by the drive.
The initiator determines that it is reselected when the SEL and I/O signals and
its SCSI ID bit are true, and the BSY signal is false for at least one bus settle
delay.
SCSI Description
3.5.4.1 Reselection Sequence
The drive:
1. Upon completing the ARBITRATION phase, asserts both the BSY and SEL
signals.
2. Delays at least one bus clear delay plus one bus settle delay.
3. Asserts the I/O signal.
4. Sets the DATA BUS to the logical OR of its SCSI ID bit and the initiator’s
SCSI ID bit.
5. Waits at least two deskew delays.
6. Releases the BSY signal.
7. Waits at least one bus settle delay before looking for a response from the
initiator.
Quantum DLT 4000 Tape Drive3-15
SCSI Description
The initiator:
8. Determines that it is selected when the following occur for at least one bus
settle delay: SEL, I/O, and the initiator’s SCSI ID bit are true and BSY is
false.
9. Examines the DATA BUS to determine the SCSI ID of the reselecting drive.
10. Asserts the BSY signal within a selection abort time of its most recent
detection of being reselected.
The initiator does not respond to a RESELECTION phase if bad parity is
detected or if more than two SCSI ID bits are on the DATA BUS.
The drive:
11. Detects the BSY signal is true.
12. Asserts the BSY signal.
13. Waits at least two deskew delays.
14. Releases the SEL signal.
15. The drive can then change the I/O signal and the DATA BUS.
The initiator:
16. Detects the SEL signal is false.
17. Releases the BSY signal.
The drive:
18. Continues asserting the BSY signal until it relinquishes the SCSI bus.
3.5.4.2 Reselection Time-Out
Two optional time-out procedures are specified for clearing the SCSI bus if the
initiator waits a minimum of a selection time-out delay and there has been no
BSY signal response from the drive.
1. The initiator asserts the RST signal.
2. The initiator follows these steps:
a) Continues asserting the SEL and ATN signals and releases the DATA
BUS.
b) If it has not detected the BSY signal to be true after at least a selection
abort time plus two deskew delays, releases the SEL and ATN signals,
allowing the SCSI bus to go to the BUS FREE phase.
3-16Quantum DLT 4000 Tape Drive
SCSI devices that respond to the RESELECTION phase must ensure that the
reselection is still valid within a selection abort time of asserting the BSY
signal.
3.5.5Information Transfer Phases
1. The tape drive supports narrow asynchronous and synchronous data transfers.
2. Both differential and single-ended versions of the tape drive are available.
3. Odd parity is generated during all information transfer phases during which the
device writes data to the SCSI bus, and parity is checked during all transfer phases
in which data is read from the bus by the tape drive. Parity checking can be
disabled (Chapter 2).
4. The ANSI SCSI specification refers to mini-libraries as “medium changers.” In this
chapter the term “mini-libraries” is used to describe these devices.
5. The DLT 4000 supports block size of 1byte to 16 Mbytes.
6. Disconnects from the SCSI bus are done at regular intervals during information
transfer phases to allow other devices to access the bus. These disconnects are
user-configurable via the Disconnect-Reconnect Page of the SCSI MODE SELECT
command.
SCSI Description
NOTES
7. The tape drive does not act as an initiator on the SCSI bus. Therefore, the drive
does not 1) generate unsolicited interrupts to the bus, 2) initiate its own SCSI
commands, and 3) assert bus reset.
8. A mini-library subsystem is assigned two logical unit numbers (LUNs): the tape
drive is always LUN 0, and the mini-library component has a default LUN of 1, but
may be reconfigured to any LUN from 0 to 15 via the SCSI MODE SELECT command.
Quantum DLT 4000 Tape Drive3-17
SCSI Description
The COMMAND, DATA, STATUS, and MESSAGE phases are known as the
Information Transfer Phases because they are used to transfer data or control
information.
The C/D, I/O, and MSG signals are used to distinguish between the different
information transfer phases (Table 3−5). The drive asserts these three signals
and so controls all information transfer phase changes. The drive can also cause
a BUS FREE phase by releasing the MSG, C/D, I/O, and BSY signals. The
initiator can request a MESSAGE OUT phase by asserting the ATN signal.
The information transfer phases use one or more REQ/ACK handshakes to
control the information transfer. Each REQ/ACK handshake allows the transfer
of one byte of information. During the information transfer phases, the BSY
signal remains true and the SEL signal remains false. Additionally, the drive
continuously envelopes the REQ/ACK handshake(s) with the C/D, I/O, and
MSG signals in such a manner that these control signals are valid for one bus
settle delay before the assertion of the REQ signal of the first handshake and
remain valid after the negation of the ACK signal at the end of the handshake of
the last transfer of the phase.
After the negation of the ACK signal of the last transfer of the phase, the drive
can prepare for a new phase by asserting or negating the C/D, I/O, and MSG
signals. These signals can be changed together or individually. They can be
changed in any order and can be changed more than once (although each line
should change only once). A new phase does not begin until the REQ signal is
asserted for the first byte of the new phase.
A phase ends when the C/D, I/O, or MSG signal changes after the negation of
the ACK signal. The time between the end of a phase and the assertion of the
REQ signal beginning a new phase is undefined. An initiator is allowed to
anticipate a new phase based on the previous phase, the expected new phase,
and early information provided by changes in the C/D, I/O, and MSG signals.
However, the anticipated phase is not valid until the REQ signal is asserted at
the beginning of the next phase.
Information Transfer Direction
True I/O Signal: from drive to initiator
False I/O Signal: from initiator to drive
3-18Quantum DLT 4000 Tape Drive
Signal
SCSI Description
Table 3–5 Information Transfer Phases
MSG
000DATA OUTInitiator to drive.
001DATA INDrive to initiator.
010COMMANDInitiator to drive.
011STATUSDrive to initiator.
110MESSAGE OUTInitiator to drive.
C/DI/OPhase NameDirection of Transfer/ Definition
Allows the drive to request that data be sent from
the initiator to the drive.
Allows the drive to send data to the initiator.
Allows the drive to request a command from the
initiator.
Allows the drive to send status information be
sent from the drive to the initiator.
Allows the drive to request that message(s) be
sent from the initiator to the drive; the drive
invokes this phase in response to the attention
condition created by the initiator.
The drive handshakes byte(s) until the ATN signal
is negated, except when rejecting a message.
See 3.5.5.4 Message Out — Additional
Conditions.
111MESSAGE INDrive to initiator.
Allows the drive to send message(s) to the
initiator.
Quantum DLT 4000 Tape Drive3-19
SCSI Description
3.5.5.1 Asynchronous Data Transfer
Drive to Initiator Transfer Procedure
1. The drive drives the DB (7–0, P) signals to their desired values.
2. Drive delays at least one deskew delay plus a cable skew delay.
3. Drive asserts the REQ signal.
4. Initiator reads the DB (7–0, P) signals.
5. Initiator indicates its acceptance of the data by asserting the ACK signal.
6. When ACK is true at the drive, drive can change or release the DB (7–0, P)
signals.
7. Drive negates the REQ signal.
8. Initiator negates the ACK signal.
9. Drive can continue the transfer by driving the DB (7–0, P) signals and
asserting the REQ signal (Steps 1 – 3).
Initiator-to-Drive Transfer Procedure
1. Drive asserts the REQ signal.
2. Initiator drives the DB (7–0, P) signals to their desired values.
3. Initiator delays at least one deskew delay plus a cable skew delay.
4. Initiator asserts the ACK signal.
5. When ACK is true at the drive, drive reads the DB (7–0, P) signals.
6. Drive negates the REQ signal.
7. Initiator can change or release the DB (7–0, P) signals.
8. Initiator negates the ACK signal.
9. Drive can continue the transfer by asserting the REQ signal (Step 1).
3.5.5.2 Synchronous Data Transfer
Synchronous Data Transfer is optional and is only used in DATA phases and
only if a synchronous data transfer agreement is established. The REQ/ACK
offset specifies the maximum number of REQ pulses that can be sent by the
drive in advance of the number of ACK pulses received from the initiator,
establishing a pacing mechanism. If the number of REQ pulses exceeds the
number of ACK pulses by the REQ/ACK offset, the drive does not assert the
3-20Quantum DLT 4000 Tape Drive
SCSI Description
REQ signal until after the leading edge of the next ACK pulse is received. For
successful completion of the data phase, the number of ACK and REQ pulses
must be equal.
The initiator sends one ACK signal pulse for each REQ pulse received. The ACK
signal can be asserted as soon as the leading edge of the corresponding REQ
pulse has been received.
Drive-to-Initiator Transfer Procedure
1. The drive sets the DB (7–0, P) signals to the desired values. The DB (7–0,
P) signals are held valid for a minimum of one deskew delay plus one cable
skew delay after REQ is asserted.
2. Drive delays at least one deskew delay plus a cable skew delay.
3. Drive asserts the REQ signal for a minimum of one assertion period. Drive
can negate the REQ signal and change or release the DB (7-0, P) signals.
4. Initiator reads the DB (7-0, P) signals within one hold time of the
transition of the REQ signal to true.
5. Initiator indicates its acceptance of the data by asserting an ACK pulse.
6. The drive waits at least the greater or these periods before again asserting
REQ:
c) A transfer period from the last transition of the REQ signal to true, or
d) A negation period from the last transition of the REQ signal to false.
7. The initiator waits at least the greater of these periods before reasserting
ACK:
a) A transfer period from the last transition of the ACK signal to true, or
b) A negation period from the last transition of the ACK signal to false.
Initiator-to-Drive Transfer Procedure
Initiator transfers one byte for each REQ pulse received.
1. Drive asserts the REQ signal.
2. After receiving the leading edge of the REQ signal, initiator drives the DB
(7–0, P) signals to their desired values. The DB (7-0, P) signals are held
valid for at least one deskew delay plus one cable skew delay plus one hold
time delay after the assertion of the ACK signal.
3. Initiator delays at least one deskew delay plus a cable skew delay.
4. Initiator asserts the ACK signal for a minimum of one assertion period.
5. Initiator can negate the ACK signal and change or release the DB (7-0, P)
signals.
Quantum DLT 4000 Tape Drive3-21
SCSI Description
6. Drive reads the DB (7-0, P) signals within one hold time of the transition of
the ACK signal to true.
7. The drive waits at least the greater of these periods before again asserting
the REQ signal:
a) A transfer period from the last transition of the REQ signal to true, or
b) A negation period from the last transition of the REQ signal to false.
8. The initiator waits at least the greater of the following periods before again
asserting the ACK signal:
a) A transfer period from the last transition of the ACK signal to true, or
b) A negation period from the last transition of the ACK signal to false.
3.5.5.3 Signal Restrictions Between Phases
When the SCSI bus is between two information transfer phases, the following
restrictions apply to the SCSI bus signals:
• The BSY, SEL, REQ, and ACK signals do not change.
• The C/D, I/O, MSG, and DATA BUS signals can change.
• When changing the DATA BUS direction from out (initiator-driving) to in
(drive-driving), the drive delays driving the DATA BUS by at least a data
release delay plus one bus settle delay after asserting the I/O signal. The
initiator releases the DATA BUS no later than a data release delay after the
transition of the I/O signal to true.
• When switching the DATA BUS from in to out, the drive releases the DATA
BUS no later than a deskew delay after negating the I/O signal.
• The ATN and RST signals can change as defined under the descriptions for
the attention condition (Section 3.6.1) and reset condition (Section 3.6.2).
3.5.5.4 STATUS Phase
The tape drive enters the status phase just once per command unless a retry is
requested by the initiator. The only exception is during error cases when the
device goes immediately to bus free, as defined in the ANSI SCSI-2 specification.
Status bytes the tape drive can return are listed in the following table:
3-22Quantum DLT 4000 Tape Drive
SCSI Description
Table 3–6 Status Bytes
Status Bytes Returned from Tape DriveDefinition
GOOD (00h)This status indicates that the drive successfully completed
the command.
CHECK CONDITION (02h)A contingent allegiance condition occurred. The REQUEST
SENSE command should be sent following this status to
determine the nature of the event.
BUSY (08h)Target is busy. This status is returned whenever the device
is unable to accept a command from an otherwise
acceptable initiator. The initiator should reissue the
command at a later time.
INTERMEDIATE GOOD (10h)This status is returned instead of GOOD for commands
issued with the LINK bit set = 1. Following the return of
this status, the drive proceeds to the COMMAND phase for
the transfer of the next linked command.
RESERVATION CONFLICT (18h)This status is returned by the drive whenever a SCSI device
attempts to access the drive when it has been reserved for
another initiator with a RESERVE UNIT command.
COMMAND TERMINATED (22h)This status is returned for a command that was terminated
via a TERMINATE I/O PROCESS message. This status also
indicates that a contingent allegiance condition has
occurred.
Quantum DLT 4000 Tape Drive3-23
SCSI Description
In contrast to the BUSY status condition, the DRIVE NOT READY
Sense Key is returned as part of the Sense data following a REQUEST
SENSE command and indicates that a media access command has
been issued but that the media is not ready to be accessed. For
example, the tape cartridge is not installed, the tape medium has
been unloaded, the tape drive is currently initializing the tape
medium to prepare it for access, etc.
In the DRIVE NOT READY state, the initiator cannot perform any
operation that would cause tape motion (READ, WRITE, VERIFY, for
example). These commands return a CHECK CONDITION status with a
DRIVE NOT READY sense key. The initiator may execute commands
that do not require tape motion or access to the tape medium, and
a GOOD status may be the result.
3.6SCSI BUS CONDITIONS
The SCSI bus has two asynchronous conditions: Attention and Reset.
NOTES
3.6.1 Attention Condition
The attention condition informs a drive that an initiator has a message ready.
The drive gets the message by performing a MESSAGE OUT phase. The
attention condition requires the following timing:
• The initiator creates the attention condition by asserting ATN at any time
except during the ARBITRATION or BUS FREE phases.
• The initiator negates the ATN signal at least two deskew delays before
asserting the ACK signal while transferring the last byte of the message.
• If the drive detects that the initiator failed to meet this requirement, then
the drive goes to BUS FREE.
• Before transition to a new bus phase, the initiator asserts the ATN signal,
then waits at least two deskew delays before negating the ACK signal for
the last byte transferred in the current bus phase. Asserting the ATN signal
later cannot be honored until a later bus phase and then cannot result in
the expected action.
The drive responds with MESSAGE OUT as described in the following table:
3-24Quantum DLT 4000 Tape Drive
SCSI Description
Table 3–7 Drive MESSAGE OUT Phase Response
ATN Signal True in Phase...The Drive Enters MESSAGE OUT…
COMMANDAfter transferring part or all of the command descriptor block
bytes.
DATAAt the drive’s earliest convenience (often on a logical block
boundary). The initiator continues REQ/ACK handshakes until it
detects the phase change.
STATUSAfter the status byte has been acknowledged by the initiator.
MESSAGE INBefore it sends another message. This permits a MESSAGE
PARITY ERROR message from the initiator to be associated with
the appropriate message.
SELECTION
1
RESELECTION
2
Immediately after that SELECTION phase.
After the drive has sent its IDENTIFY message for that
RESELECTION phase.
1
Before the initiator releases BSY, provided the initiator asserted ATN.
2
The initiator should only assert the ATN signal during a RESELECTION phase to transmit a BUS
DEVICE RESET or DISCONNECT message.
The initiator keeps the ATN signal asserted if more than one byte is to be
transferred. The initiator can negate the ATN signal at any time, except it does
not negate the ATN signal while the ACK signal is asserted during a MESSAGE
OUT phase. Normally, the initiator negates the ATN signal while the REQ
signal is true and the ACK signal is false during the last REQ/ACK handshake
of the MESSAGE OUT phase.
3.6.2 Reset Condition
The tape drive responds to power-on and/or bus reset conditions as described:
• All tape drive SCSI lines assert high impedance when the tape drive is
powered off.
• The drive does not generate any spurious signals on the SCSI bus when the
drive is powered on.
• Within five (5) seconds of power-on, and within 250 milliseconds (typically
under 4 milliseconds) after a bus reset, the tape drive responds to SCSI bus
selections and returns the appropriate normal responses. Tape motion
Quantum DLT 4000 Tape Drive3-25
SCSI Description
commands are returned with Check Condition status, Sense Key of Not
Ready, until the medium has been made ready.
• The tape medium is rewound to Beginning of Partition (BOP, i.e.,
Beginning of Tape [BOT]).
Note that the tape drive does not implement the hard reset alternative for bus
RESET processing.
The tape drive recognizes multiple bus resets in succession as well as bus resets
of arbitrarily long duration (powering on conditions). It recovers within the time
limits specified above following the last bus reset.
3.6.3 Queued Unit Attentions
Queued Unit Attentions are implemented on the tape drive and are maintained
separately for each valid LUN for each initiator. Unit Attentions are created as a
result of the following circumstances:
• Power on
• Bus reset
• Bus device reset message
• When the media may have changed asynchronously
• When another initiator has changed the mode parameters
• When a firmware (microcode) update has completed
Two (2) queued Unit Attentions are not unusual. For example, if a drive is
powered up and a cartridge is loaded, “power up” and “not ready to ready
transition” Unit Attention messages are created. Due to a limited number of
Unit Attention buffers, if an initiator does not clear Unit Attentions queued for
it, the tape drive at some point stops generating new Unit Attention messages
for the Initiator-Logical Unit (I-L) combination (existing messages remain
queued).
A LOAD command does not generate a Unit Attention message for the initiator
that issued the command, since the transition to ready is synchronous.
3-26Quantum DLT 4000 Tape Drive
Chapter 4
MESSAGES
The SCSI message system allows communication between an initiator and the drive for interface
management and command qualification. Messages can be originated by either the initiator or the
drive. This section contains a detailed description of the messages supported by the drives.
4.1MESSAGE FORMAT
A message can be one or more bytes in length. One or more messages can be
sent during a single MESSAGE phase, but a message cannot be split over
MESSAGE phases. The initiator is required to end the MESSAGE OUT phase
(by negating ATN) when it sends certain messages that are identified in Table
4–2.
When a connection to the drive is established (i.e., the drive is selected with
ATN asserted), the first message byte passed by the initiator must be either an
IDENTIFY, ABORT, or BUS DEVICE RESET message. If not, the drive discards
the message, saves no status information, and goes to the BUS FREE phase.
If an initiator supplies an unsupported message (for example, COMMAND
COMPLETE or a reserved or undefined message code), the drive returns a
MESSAGE REJECT message and continues where it left off (possibly returning
to MESSAGE OUT if ATN is raised).
The first byte of the message, as defined in Table 4–1, determines the format of
the message.
Quantum DLT 4000 Tape Drive4-1
Messages
Table 4–1 Message Format
Message CodeMessage
00hOne-byte message (COMMAND COMPLETE)
01hExtended message
02h – 1FhOne-byte message
20h – 2FhTwo-byte message
40h – 7FhReserved
80h – FFhOne-byte message (IDENTIFY)
The DLT 4000 tape drive supports the messages listed in Table 4–2. The
message code and the direction of the message flow is also included in the table
(In = target to initiator, Out = initiator to target).
4-2Quantum DLT 4000 Tape Drive
Table 4–2 Supported Messages
MessageMessage CodeDirection
ABORT06hOut
BUS DEVICE RESET0ChOut
COMMAND COMPLETE00hIn
DISCONNECT04hInOut
Messages
EXTENDED MESSAGE (Synchronous Data
Transfer Request, or SDTR)
IDENTIFY80h – FFhInOut
INITIATOR DETECTED ERROR05hOut
LINKED COMMAND COMPLETE0AhIn
LINKED COMMAND COMPLETE (with flag)0BhIn
MESSAGE PARITY ERROR09hOut
MESSAGE REJECT07hIn
NO OPERATION08hOut
RESTORE POINTERS03hIn
SAVE DATA POINTER02hIn
*
Extended message (Figure 4–1); described in Section 4.2.14.
*
01hInOut
Two-byte messages consist of two consecutive bytes. The value of the first byte,
as defined in Table 4–1, determines which message is to be transmitted. The
second byte is a parameter byte that is used as defined in the message
description.
A value of 1 in the first byte indicates the beginning of a multiple-byte extended
message. The minimum number of bytes sent for an extended message is three.
The extended message format is shown in Figure 4–1 and the data fields are
described in Table 4–3.
Quantum DLT 4000 Tape Drive4-3
Messages
Bit
Byte
0 Extended Message (01h)
1Extended Message Length
2Extended Message Code
3 to n-1 Extended Message Arguments
76543210
Figure 4–1 Extended Message - Data Format
Table 4–3 Extended Message - Field Description
FieldDescription
Extended Message
Length
This field specifies the length, in bytes, of the Extended
Message Code plus the Extended Message Arguments that
follow. Therefore, the total length of the message is equal to
the Extended Message Length plus 2.
A value of 0 for the Extended Message Length indicates that
256 bytes follow.
Extended Message CodeThe drive supports some Extended Messages. They are:
01h SYNCHRONOUS DATA TRANSFER REQUEST
80h – FFh Vendor Unique (for more information, refer to the
section for the INQUIRY command in Chapter 5).
4-4Quantum DLT 4000 Tape Drive
4.2SUPPORTED SCSI MESSAGES
Following are descriptions of each of the messages supported by the drive.
4.2.1 ABORT Message (06h)
This message is sent from the initiator to the target to clear the current I/O
process on the selected unit. Buffered (cached) write operations are completed if
possible. The target goes directly to the BUS FREE phase after successful receipt
of this message. Current settings of MODE SELECT parameters and
reservations are not affected. Commands, data, and status for other initiators
are not affected.
This message can be sent to a logical unit that is not currently performing an
operation for the initiator. If no unit has been selected, the target goes to BUS
FREE phase and no commands, data, or status on the target are affected.
4.2.2 BUS DEVICE RESET Message (0Ch)
The BUS DEVICE RESET message is sent from an initiator to direct the drive to
clear all I/O processes on the drive. The message causes the drive to:
Messages
1.Flush the contents of cache to tape and go to the BUS FREE phase.
2.Execute a hard reset, leaving it as if a Bus Reset had occurred.
The drive creates a Unit Attention condition for all initiators after accepting and
processing a Bus Device Reset message. The additional sense code is set to
POWER ON, RESET, or BUS DEVICE RESET OCCURRED.
4.2.3 COMMAND COMPLETE Message (00h)
The COMMAND COMPLETE message is sent by the drive to an initiator to
indicate that an I/O process has completed and that valid status has been sent
to the initiator. After successfully sending this message, the drive goes to the
BUS FREE phase by releasing the BSY signal. The drive considers the message
transmission successful when it detects the negation of ACK for the
COMMAND COMPLETE message with the ATN signal false. If a COMMAND
COMPLETE message is received by the tape drive, it is handled as an illegal
message: the drive returns MESSAGE REJECT and enters its STATUS phase,
reporting CHECK CONDITION with the sense key set to COMMAND
ABORTED.
Quantum DLT 4000 Tape Drive4-5
Messages
4.2.4 DISCONNECT Message (04h)
The DISCONNECT message is sent from the drive to inform the initiator that
the present connection is going to be broken (the drive plans to disconnect by
releasing the BSY signal) and a later reconnect will be required to complete the
current I/O process. The message does not cause the initiator to save the data
pointer. After sending the message, the drive goes to the BUS FREE phase by
releasing the BSY signal.
The DISCONNECT message can also be sent by the initiator to tell the drive to
suspend the current phase and disconnect from the bus. The drive’s response to
and its handling of a DISCONNECT message are based on when, in the I/O
process, the initiator introduces the DISCONNECT message. Table 4–4
summarizes the drive’s response.
Table 4–4 Drive Response to DISCONNECT Message
BUS PhaseDrive Response
SELECTIONThe drive discards the DISCONNECT message and goes to BUS FREE.
COMMANDThe drive discards the DISCONNECT message and goes to BUS FREE. The
ATTENTION request is ignored while the Command Descriptor Block is fetched.
The drive does not switch to MESSAGE OUT until the current DMA completes.
DATAThe ATTENTION request is ignored while the current data transfer completes;
that is, the drive does not switch to MESSAGE OUT until after the current DMA
completes. The drive returns a MESSAGE REJECT message and responds with
CHECK CONDITION status, indicating the command aborted because of an
invalid message.
STATUSThe drive sends a MESSAGE REJECT message, then sends COMMAND
COMPLETE.
MESSAGE INThe drive sends a MESSAGE REJECT message and switches to the BUS FREE
phase.
4-6Quantum DLT 4000 Tape Drive
4.2.5 IDENTIFY Message (80h - FFh)
The IDENTIFY message is sent by either the initiator or the drive to establish or
re-establish the physical connection path between an initiator and target for a
particular logical unit, under the conditions listed below. Figure 4–2 shows the
format of the IDENTIFY message and Table 4–5 describes the data field
contents.
Messages
Bit
Byte
76543210
IdentifyDiscPriv
LUNTAR
ReservedLUNTRAN
Figure 4–2 IDENTIFY Message - Data Format
Table 4–5 IDENTIFY Message - Field Description
FieldDescription
IdentifyThe Identify bit must be set to 1. This identifies the message as an IDENTIFY
message.
DiscPrivDisconnect Privilege. The DiscPriv can be 0, provided that no other I/O process is
currently active in the drive. If not set to 1 and other I/O processes are currently
active in the drive, the drive returns BUSY status.
LUNTARThe Logical Unit/Target Routine (LUNTAR) field must be set to zero. The drive
supports a single Logical Unit Number (LUN 0 ). A LUNTAR bit of one causes the
drive to send a MESSAGE REJECT message and switch to the BUS FREE phase.
ReservedThe Reserved bits must be zero. If a Reserved bit is non-zero, the drive returns a
MESSAGE REJECT message and switches to the BUS FREE phase.
LUNTRNLogical Unit Number.
Quantum DLT 4000 Tape Drive4-7
Messages
4.2.6 INITIATOR DETECTED ERROR Message (05h)
The INITIATOR DETECTED ERROR message is sent from an initiator to
inform the drive that an error has occurred that does not preclude the drive from
retrying the operation (a bus parity error, for example). The source of the error
may either be related to previous activities on the SCSI bus or may be only driverelated. When received, the tape drive attempts to re-transfer the last command,
data, or status bytes by using the RESTORE POINTER message mechanism.
The drive’s response to and its handling of an INITIATOR DETECTED ERROR
message are based on when, in the I/O process, the initiator introduces the
message. Table 4–6 summarizes the drive’s response.
Table 4–6 Drive Response to INITIATOR DETECTED ERROR Message
BUS PhaseDrive Response
SELECTIONThe drive discards the INITIATOR DETECTED ERROR message and then goes
to the BUS FREE phase.
COMMANDThe drive discards any Command Descriptor Block bytes fetched from the
initiator, sets the Sense Key to ABORTED COMMAND, sets the Additional
Sense Code to INITIATOR DETECTED ERROR MESSAGE RECEIVED. It sends
the CHECK CONDITION status and the COMMAND COMPLETE message and
then goes to the BUS FREE phase.
DATAThe drive discards the INITIATOR DETECTED ERROR message and sets the
Sense Key to ABORTED COMMAND, sets the Additional Sense Code to
INITIATOR DETECTED ERROR MESSAGE RECEIVED. It sends the CHECK
CONDITION status and the COMMAND COMPLETE message and then goes
to the BUS FREE phase.
STATUSThe drive sends a RESTORE POINTERS message, returns to the STATUS
phase, resends the STATUS command, and continues the I/O process.
MESSAGE INThe drive discards the INITIATOR DETECTED ERROR message and sets the
Sense Key to ABORTED COMMAND, sets the Additional Sense Code to
INITIATOR DETECTED ERROR MESSAGE RECEIVED. It sends the CHECK
CONDITION status and the COMMAND COMPLETE message and then goes
to the BUS FREE phase.
4-8Quantum DLT 4000 Tape Drive
4.2.7 LINKED COMMAND COMPLETE Message (0Ah)
This message is sent from a target to an initiator to indicate that the execution
of a linked command (with the FLAG bit set to zero) is complete and that
status has been sent. The initiator then sets the pointers to the initial state for
the next command.
If received by a target, this message is handled as an illegal message; the drive
enters the MESSAGE IN phase and returns MESSAGE REJECT.
4.2.8 LINKED COMMAND COMPLETE, with Flag Message (0Ah)
This message is sent from a target to an initiator to indicate that the execution
of a linked command (with the FLAG bit set to one) is complete and that status
has been sent.
4.2.9 MESSAGE PARITY ERROR Message (09h)
This message is sent from the initiator to tell the drive that the last message
byte the drive passed on to the initiator contained a parity error.
To indicate that it intends to send the message, the initiator sets the ATN
signal before it releases ACK for the REQ/ACK handshake of the message that
has the parity error. This provides an interlock so that the target can determine
which message has the parity error. If the target receives this message under any
other condition, it proceeds directly to the BUS FREE state by releasing the BSY
signal, signifying a catastrophic error.
Messages
The target’s response to this message is to switch to the MESSAGE IN phase
and re-send from the beginning all the bytes of the message that precipitated the
MESSAGE PARITY ERROR message.
4.2.10 MESSAGE REJECT Message (07h)
This message is sent from the initiator or target to indicate that the last
message received was inappropriate or has not been implemented.
To indicate its intention to send this message, the initiator asserts the ATN
signal before it releases ACK for the REQ/ACK handshake of the message that
is to be rejected. MESSAGE REJECT is issued in response to any message the
drive considers to be illegal or not supported. When sending to the initiator, the
tape drive does so before requesting any additional message bytes.
Quantum DLT 4000 Tape Drive4-9
Messages
4.2.11 NO OPERATION Message (08h)
If a target requests a message, the initiator sends a NO OPERATION message if
it does not currently have any other valid message to send. The message is
accepted when the drive is acting as a target and may be sent when it is an
initiator. If a NO OPERATION message is received during a selection, the drive
proceeds to the COMMAND phase (provided ATN does not continue as
asserted); the NO OPERATION message is ignored by the tape drive.
4.2.12 RESTORE POINTERS Message (03h)
The RESTORE POINTERS message is sent from the drive to the initiator to
direct the initiator to copy the most recently saved command, data, and status
pointers for the I/O process to the corresponding current pointers. The command
and status pointers are restored to the beginning of the present command and
status areas. The data pointer is restored to the value at the beginning of the
data area in the absence of a SAVE DATA POINTER message or to the value at
the point at which the last SAVE DATA POINTER message occurred for that
logical unit.
When the RESTORE POINTERS message is received as a target, the target
switches to the message in phase and returns MESSAGE REJECT.
4.2.13 SAVE DATA POINTER Message (02h)
The SAVE DATA POINTER message is sent from the drive to direct the
initiator to copy the current data pointer to the saved data pointer for the
current I/O process.
When functioning as a target, the tape drive sends this message before a
disconnect during a data transfer. It does not send a SAVE DATA POINTER
message if it intends to move directly to STATUS phase. When received as a
target, it switches to message in phase and returns MESSAGE REJECT.
4.2.14 SYNCHRONOUS DATA TRANSFER REQUEST Message (01h)
This extended message allows the target and initiator to agree on the values of
the parameters relevant to synchronous transfers. The tape drive will not initiate
the Synchronous Data Transfer Request message; it relies on the initiator to do
so. The Synchronous Data Transfer Request command has the format shown in
Figure 4-3.
4-10Quantum DLT 4000 Tape Drive
Messages
Bit
Byte
0Extended Message Identifier (01h)
1Length (03h)
2Message Code (01h)
3
4
76543210
(Figure 4-1)
Transfer Period: Min. = 50 (32h)
Transfer REQ/ACK Offset: Max. = 15
Figure 4–3 Synchronous Data Transfer Request Message - Data Format
NOTE
The tape drive supports initiating synchronous transfer negotiations
with the host, but this feature is disabled by default. To enable it,
set the MODE SELECT VU ERROM parameter EnaInitSyncNeg.
Quantum DLT 4000 Tape Drive4-11
Messages
4-12Quantum DLT 4000 Tape Drive
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