Seagate, Seagate Technology, and the Seagate logo are registered trademarks of Seagate
Technology LLC. SeaTools, SeaFONE, SeaBOARD, and SeaTDD are either registered trade
marks or trademarks of Seagate Technology LLC. Other product names are registered trademarks or trademarks of their owners.
Seagate reserves the right to change , without notice, product offerings or specifications. No part
of this publication may be reproduced in any fo rm without written permission of Seagate Technol
This manual describes Seagate Technology® LLC, Cheetah® SAS (Serial Attached SCSI) disc drives.
Cheetah drives support the SAS Protocol specifications to the extent described in this manual. The SAS Inter-
face Manual (part number 100293071) describes the general SAS characteristics of Cheetah T10 and other
Seagate SAS drives.
Figure 1. Cheetah T10 SAS disc drive
Cheetah T10 SAS Product Manual, Rev. A1
2Cheetah T10 SAS Product Manual, Rev. A
2.0Sta ndards, compliance and reference documents
The drive has been developed as a system peripheral to the highest standards of design and construction. The
drive depends on its host equipment to provide adequate power and environment for optimum performance
and compliance with applicable industry and governmental regulations. Special attention must be given in th e
areas of safety, power distribution, shielding, audible noise control, and temperature regulation. In particular,
the drive must be securely mounted to guar antee the specified performance characteristics. Mounting by bot
tom holes must meet the requirements of Section 8.3.
2.1Standards
The Cheetah SAS family complies with Seagate standards as noted in the appropriate sections of this manual
and the Seagate SAS Interface Manual, part number 100293071.
The Cheetah disc drive is a UL recog nized com pon en t pe r UL1950 , CSA certified to CAN/CSA C22.2 No. 95095, and VDE certified to VDE 0805 and EN60950.
2.1.1Electromagnetic compatibility
The drive, as delivered, is designed for system integration and installation into a suitable enclosure prior to
use. The drive is supplied as a subasse mbly and is not s ubject to Subpart B o f Part 15 of the F CC Rules and
Regulations nor the Radio Interference Reg ula tio ns of the Canadian Department of Communications.
The design characteristics of the drive serve to minimize radiation when installed in an enclosure that provides
reasonable shielding. The drive is capable of meeting the Class B limits of the FCC Rules and Regulations of
the Canadian Department of Communications when properly packaged; however, it is the user ’s responsibility
to assure that the drive meets the appropriate EMI requirements in their system. Shielded I/O cables may be
required if the enclosure does not provide adequate shielding. If the I/O c ables are external to the enclosure,
shielded cables should be used, with the shields grounded to the enclosure and to the host controller.
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2.1.1.1Electromagnetic susceptibility
As a component assembly, the drive is not required to meet any susceptibility performance requirements. It is
the responsibility of those integrating the drive within their systems to perform those tests required and design
their system to ensure that equipment operating in the same system as the drive or external to the system
does not adversely affect the performance of the drive. See Tables
Cheetah T10 SAS Product Manual, Rev. A3
2, 3 and 4, for DC power requirements.
2.2Compliance
2.2.1Electromagnetic compliance
Seagate uses an independent laboratory to confirm compliance with the directives/standards for CE Marking
and C-Tick Marking. The drive was teste d in a repr esent ative system for typical applications. The selected sys
tem represents the most popular characteristics for test platforms. The system configurations include:
• Typical current use microprocessor
• 3.5-inch floppy disc drive
• Keyboard
• Monitor/display
• Printer
• External modem
•Mouse
Although the test system with this Seagate model complies with the directives/standards, we cannot guarantee
that all systems will comply. The computer manufacturer or system integrator shall confirm EMC compliance
and provide the appropriate marking for their product.
Electromagnetic compliance for the European Union
If this model has the CE Marking it complies with the European Union requirements of the Electromagnetic
Compatibility Directive 89/336/EEC of 03 May 1989 as amended by Directive 92/31/EEC of 28 April 1992 and
Directive 93/68/EEC of 22 July 1993.
-
Australian C-Tick
If this model has the C-Tick Marking it complies with the Australia/New Zealand Standard AS/NZS3548 1995
and meets the Electromagnetic Compatibility (EMC) Framework requirements of Australia’s Spectrum Man
agement Agency (SMA).
Korean MIC
If this model has the Korean Ministry of Information and Communication (MIC) logo, it complies with paragraph
1 of Article 11 of the Electromagnetic Compatibility (EMC) Control Regulation and meets the Electromagnetic
Compatibility Framework requirements of the Radio Research Laboratory (RRL) Ministry of Information and
Communication Republic of Korea.
Taiwanese BSMI
If this model has two Chinese words meaning “EMC certification” followed by an eight digit identification num-
ber, as a Marking, it complies with Chinese National Standard (CNS) 13438 and meets the Electromagnetic
Compatibility (EMC) Framework requirements of the Taiwanese Bureau of Standards, Metrology, and Inspec
tion (BSMI).
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4Cheetah T10 SAS Product Manual, Rev. A
2.3Reference documents
Cheetah T10 SAS Installation GuideSeagate part number: 100433695
SCSI Commands Reference ManualSeagate part number: 100293068
SAS Interface ManualSeagate part number: 100293071
Applicable ANSI SAS documents
SFF-83233.5” Drive Form Factor with Serial Connector
SFF-8460HSS Backplane Design Guidelines
SFF-8470Multi Lane Copper Connector
SFF-8482SAS Plug Connector
ANSI INCITS.xxx Serial Attached SCSI (SAS) Standard (T10/1562-D)
ISO/IEC 14776-xxx SCSI Architecure Model-3 (SAM-3) Standard (T10/1561-D)
ISO/IEC 14776-xxx SCSI Primary Commands-3 (SPC-3) Standard (T10/1416-D)
ISO/IEC 14776-xxx SCSI Block Commands-2 (SBC-2) St andard (T10/1417-D)
ANSI Small Computer System Interface (SCSI) Documents X3.270-1996(SCSI-3) Architecture Model
Specification for Acoustic Test Requirement and ProceduresSeagate part number: 30553-001
Package Test SpecificationSeagate P/N 30190-001 (under 100 lb.)
Package Test SpecificationSeagate P/N 30191-001 (over 100 lb.)
In case of conflict between this document and any referenced document, this document takes precedence.
Cheetah T10 SAS Product Manual, Rev. A5
6Cheetah T10 SAS Product Manual, Rev. A
3.0General description
Cheetah drives combine giant magnetoresistive (GMR) heads, partial response/maximum likelihood (PRML)
read channel electronics, embedded servo technology, and a Serial Attached SCSI (SAS) interface to provide
high performance, high capacity data storage for a variety of systems including engineering workstations, net
work servers, mainframes, and superc om p uter s. T he Serial Attached SCSI interface is designed to meet nextgeneration computing demands for performance, scalability, flexibility and high-density storage requirements.
Cheetah drives are random access storage devices designed to support the Serial Attached SCSI Protocol as
described in the ANSI specifications, this document, and the SAS Interface Manual (part number 100293071)
which describes the general interface characteristics of this drive. Cheetah drives are classified as intelligent
peripherals and provide level 2 conformance (highest level) with the ANSI SCSI-1 standard. The SAS connec
tors, cables and electrical interface are compatible with Serial ATA (SATA), giving future users the choice of
populating their systems with either SAS or SATA hard disc drives. This allows you to continue to leverage your
existing investment in SCSI while gaining a 3Gb/s serial data transfer rate.
The head and disc assembly (HDA) is sealed at the factory. Air recirculates within the HDA through a nonreplaceable filter to maintain a contamination-free HDA environment.
Note.Never disassemble the HDA and do not attempt to service items in the sealed enclosure (heads,
media, actuator, etc.) as this requires special facilities. The drive does not contain user-replaceable
parts. Opening the HDA for any reason voids your warranty.
Cheetah drives use a dedicated landing zone at the innermost radius of the media to eliminate the possibility of
destroying or degrading data by landin g in the dat a zone. The heads automatically go to the landing zone when
power is removed from the drive.
-
-
An automatic shipping lock prevents potential damage to the heads and discs that results from movement during shipping and handling. The shipping lock disengages and the head load process begins when power is
applied to the drive.
Cheetah drives decode track 0 location data from the servo data embedded on each surface to eliminate
mechanical transducer adjustments and related reliability concerns.
The drives also use a high-performance actuator assembly with a low-inertia, balanced, patented, straight arm
design that provides excellent performance with minimal power dissipation.
Cheetah T10 SAS Product Manual, Rev. A7
3.1Standard features
Cheetah drives have the following standard features:
• 1.5 / 3Gbit Serial Attached SCSI (SAS ) interface
• Integrated dual port SAS controller supporting the SCSI protocol
• Support for SAS expanders and fanout adapters
• Firmware downloadable using the SAS interface
• 128-deep task set (queue)
• Supports up to 32 initiators
• Jumperless configuration.
• User-selectable logical block size (512, 520, 524, or 528 bytes per logical block)
• Perpendicular recording technology
• Programmable logical block reallocation scheme
• Flawed logical block reallocation at format time
• Programmable auto write and read reallocation
• Reallocation of defects on command (Post Format)
• ECC maximum burst correction length of 320 bits
• No preventive maintenance or adjustments required
• Dedicated head landing zone
• Embedded servo design
• Automatic shipping lock
• Embedded servo design
• Self diagnostics performed when power is applied to the drive
• Zone bit recording (ZBR)
• Vertical, horizontal, or top down mounting
• Dynamic spindle brake
• 16 Mbyte data buffer (see Section 4.5).
• Drive Self Test (DST)
• Background Media Scan (BGMS)
•Power Save
3.2Media description
The media used on the drive has an aluminum substrate coated with a thin film magnetic material, ov e rcoa t ed
with a proprietary protective layer for improved durability and environmental protection.
3.3Performance
• Programmable multi-segmentable cache buffer
• 300 Mbytes/sec maximum instantaneous data transfers.
• 15k RPM spindle. Average latency = 2.0 msec
• Background processing of queue
• Supports start and stop commands (spindle stops spinning)
• 1,400,000 hour MTBF (Annualized Failure Rate (AFR) of 0.62%)
• Incorporates industry-standard Self-Monitoring Analysis and Reporting Technology (S.M.A.R.T.)
• 5-year warranty
3.5Formatted capacities
Standard OEM models are formatted to 512 bytes per block. The block size is selectable at format time and
must be a multiple of 4 bytes. Users having the necessary equipment may modify the data block size before
issuing a format command and obtain different formatted capacities than those listed.
To provide a stable target capacity environment and at the same time provide users with flexibility if they
choose, Seagate recommends product planning in one of two modes:
1. Seagate designs specify capacity points at ce rtain block sizes that Seagate guarantees current and future
products will meet. We recommend customers use this capacity in their project planning, as it ensures a
stable operating point with backward and forward compatibility from generation to generation. The current
guaranteed operating points for this product are:
2. Seagate drives also may be use d at the maximu m ava ilable capacity at a give n blo ck size , but the exce ss
capacity above the guaranteed level will vary between other drive families and from generation to genera
tion, depending on how each block size actually formats out for zone frequencies and splits over servo
bursts. This added capacity potential may range from 0.1 to 1.3 percent above the guaranteed capacities
listed above. Using the drives in this manner gives the absolute maximum capacity potential, but the user
must determine if the extra capacity potential is useful, or whether their assurance of backward and for
ward compatibility takes precedence.
3.6Programmable drive capacity
Using the Mode Select command, the drive can change its capacity to something less than maximum. See the
Mode Select (6) parameter list table in the SAS Interface Manual, part number 100293071. A value of zero in
the Number of Blocks field indicates that the drive will not change the capacity it is currently formatted to have.
A number other than zero and less than the maximum number of LBAs in the Number of Blocks field changes
the total drive capacity to the value in the Number of Blocks field. A value greater than the maximum numbe r of
LBAs is rounded down to the maximum capacity.
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3.7Factory-installed accessories
OEM standard drives are shipped with the Cheetah T10 SAS Installation Guide, part number 100433695, and
the Safety and Regulatory Agency Specifications, part number 75789512 (unless otherwise specified).
Cheetah T10 SAS Product Manual, Rev. A9
3.8Options (factory installed)
You may order the following items which are incorporated at the manufacturing facility during production or
packaged before shipping. Some of the options available are (not an exhaustive list of possible options):
• Other capacities can be ordered depending on sparing scheme and sector size requested.
• Single-unit shipping pack. The drive is normally shipped in bulk packaging to provide maximum protec tion
against transit damage. Units shipped individually require additional protection as p rovided by the sin gle unit
shipping pack. Users planning single unit distribution should specify this option.
•The Cheetah T10 SAS Installation Guide, part number 100433695, is usually included with each standard
OEM drive shipped, but extra copies may be ordered.
•The Safety and Regulatory Agency Specifications, part number 75789512, is usually included with each
standard OEM drive shipped, but extra copies may be ordered.
3.9User-installed accessories
The following accessory is available:
• Single-unit shipping pack.
10Cheetah T10 SAS Product Manual, Rev. A
4.0Performance characteristics
This section provides detailed information concerning performance-related characteristics and features of
Cheetah drives.
4.1Internal drive characteristics
ST3300555SS ST3146755SS ST373355SS
Drive capacity300.0146.873.4Gbytes (formatted, rounded off value)
Read/write data heads842
Tracks per surface (total)74,34074,34074,340Tracks (user accessible)
Tracks per inch125,000125,000125,000TPI
Peak bits per inch890k890k890kKBPI
Areal Density110110110Gbits/inch
Internal data rate960 to 1607960 to 1607960 to 1607Mbits/sec (variable with zone)
Disc rotation speed15k15k15krpm
Avg rotational latency2.02.02.0msec
*One Gbyte equals one billion bytes when referring to hard drive capacity. Accessible capacity may vary depending on operating environment
and formatting.
**Rounded off value.
2
*,**
4.2Seek time
See Section 9.4.1, "SAS physical interface" on page 57 and the SAS Interface Manual (part number
100293071) for additional timing details.
4.2.1Access time
Not Including controller overhead
ReadWrite
AverageTypical3.54.0
Single trackTypical0.20.4
Full strokeTypical6.87.5
1, 2
(msec)
1.Typical access times are measured under nominal conditions of temperature, voltage,
and horizontal orientation as me asured on a representative sample of drives.
2.Access to data = access time + latency time.
Cheetah T10 SAS Product Manual, Rev. A11
4.2.2Format command execution time (minutes)
ST3300555SSST3146755SSST373355SS
Maximum (with verify)
Maximum (without verify)
1459060
904530
Execution time measured from receipt of the last byte of the Command Descriptor Block (CDB) to the request
for a Status Byte Transfer to the Initiator (excluding connect/disconnect).
4.2.3General performance characteristics
Sustainable disc transfer rate*:
Minimum55.5 Mbytes/sec
Maximum93 Mbytes/sec
SAS Interface maximum instantaneous transfer rate300 Mbytes/sec* per port
Logical block sizes
Default is 512-byte data blocks
Sector sizes variable to 512, 520, 524 an 528 bytes.
Read/write consecutive sectors on a trackYes
Flaw reallocation performance impact (for flaws reallocated at format time using
the spare sectors per sparing zone reallocation scheme.)
Average rotational latency2.0 msec
*Assumes system ability to support the rates listed and no cable loss.
(dual port = 600 Mbytes/sec*)
Negligible
4.3Start/stop time
The drive accepts the commands listed in the SAS Interface Manual less than 3 seconds after DC power has
been applied.
If the drive receives a NOTIFY (ENABLE SPINUP) primitive through either port and has not received a START
STOP UNIT command with the START bit equal to 0, the drive becomes ready for normal operations within 20
seconds (excluding the error recovery procedure).
If the drive receives a START STOP UNIT command with the START bit equal to 0 before receiving a NOTIFY
(ENABLE SPINUP) primitive, the drive waits for a START ST OP UNIT command with the START bit equal to 1.
After receiving a START STOP UNIT command with the START bit equal to 1, the drive waits for a NOTIFY
(ENABLE SPINUP) primitive. After receiving a NOTIFY (ENABLE SPINUP) primitive through either port, the
drive becomes ready for normal operations within 20 seconds (excluding the error recovery procedure).
If the drive receives a START STOP UNIT command with the START bit and IMMED bit equal to 1 and does
not receive a NOTIFY (ENABLE SPINUP) primitive within 5 seconds, the drive fails the START STOP UNIT
command.
12Cheetah T10 SAS Product Manual, Rev. A
The ST AR T STOP UNIT command may be used to command the drive to stop the spindle. Stop time is 30 seconds (maximum) from removal of DC power. There is no power control switch on the drive.
4.4Prefetch/multi-segmented cache control
The drive provides a prefetch (read look-ahead) and multi-segmented cache control algorithms that in many
cases can enhance system performance. Cache refers to the drive buffer storage space when it is used in
cache operations. To select this feature, the host sends the Mode Select command with the proper va lues in
the applicable bytes in page 08h. Prefetch and cache operations are independent features from the standpoint
that each is enabled and disabled independently using the Mode Select command; however, in actual opera
tion, the prefetch feature overlaps cache operation somewhat as described in sections 4.5.1 and 4.5.2.
All default cache and prefetch mode parameter values (Mode Page 08h) for standard OEM versions of this
drive family are given in Section
9.3.2.
4.5Cache operation
Note.Refer to the SAS Interface Manual for more detail concerning the cache bits.
Of the 16 Mbytes physical buffer space in the drive, approximately 13,000 kbytes can be used as a cache. The
buffer is divided into logical segments from which data is read and to which data is written.
The drive keeps track of the logical block addresses of the data stored in each segment of the buffer. If the
cache is enabled (see RCD bit in the SAS Interface Manual
is retrieved from the buffer, if possible, before any disc access is initiated. If cache operation is not enabled, the
buffer is still used, but only as circular buffer segments during disc medium read operations (disregarding
Prefetch operation for the moment). That is, the drive does not check in the buffer segments for the requested
read data, but goes directly to the medium to retrieve it. The retrieved data merely passes through some buffer
segment on the way to the host. All data transfers to the host are in accordance with buffer-full ratio rules. See
the explanation provided with the information about Mode Page 02h (disconnect/reconnect control) in the SAS
Interface Manual.
), data requested by the host with a read comman d
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The following is a simplified description of the prefetch/cache operation:
Case A—read command is received and all of the requested logical blocks are already in the cache:
1. Drive transfers the requested logical blocks to the initiator.
Case B—A Read command requests data, and at least one requested logical block is not in any segment of
the cache:
1. The drive fetches the requested logical blocks from the disc and transfers them into a segment, and then
from there to the host in accordance with the Mode Select Disconnect/Reconnect parameters, page 02h.
2. If the prefetch feature is enabled, refe r to sec tio n 4.5.2 for operation from this point.
Each cache segment is actually a self-contained circular buffer whose length is an integer number of logical
blocks. The drive dynamically creates and removes segments based on the workload. The wrap-around capa
bility of the individual segments greatly enhances the cache’s overall performance.
Note.The size of each segment is not reported by Mode Sense command page 08h, bytes 14 and 15.
The value 0XFFFF is always reported regardless of the actual size of the segment. Sending a size
specification using the Mode Select command (bytes 14 and 15) does not set up a new segment
size. If the STRICT bit in Mode page 00h (byte 2, bit 1) is set to one, the drive responds as it does
for any attempt to change an unchangeable parameter.
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Cheetah T10 SAS Product Manual, Rev. A13
4.5.1Caching write data
Write caching is a write operation by the drive that ma kes use o f a drive b uffer storage area wher e the da ta to
be written to the medium is stored while the drive performs the Write command.
If read caching is enabled (RCD=0), then data written to the medium is retained in the cache to be made available for future read cache hits. The same buffer space and segmentation is used as set up for read functions.
The buffer segmentation scheme is set up or changed independently, having nothing to do with the state of
RCD. When a write command is issued, if RCD=0, the cache is first checked to see if any logical blocks that
are to be written are already stored in the cache from a previous read or write command. If there are, the
respective cache segments are cleared. The new data is cached for subsequent Read commands.
If the number of write data logical blocks exceed the size of the se gment being written into, when the end of the
segment is reached, the data is written into the beginning of the same cache segment, overwriting the data that
was written there at the beginning of the operation; however, the drive does not overwrite data that has not yet
been written to the medium.
If write caching is enabled (WCE=1), then the drive may return Good status on a write command after the data
has been transferred into the cache, but before the data has been written to the medium. If an error occurs
while writing the data to the medium, and Good status has already been returned, a deferred error will be gen
erated.
The Synchronize Cache command may be used to force the drive to write all cached write data to the medium.
Upon completion of a Synchronize Cache command, all data received from previous write commands will have
been written to the medium.
Tables 10, 11, and 12 shows the mode default settings for the drives.
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4.5.2Prefetch operation
If the Prefetch feature is enabled, data in contiguous logical blocks on the disc immediately beyond that which
was requested by a Read command are retrieved and stored in the buffer for immediate transfer from the
buffer to the host on subsequent Read commands that request those logical blocks (this is true even if cache
operation is disabled). Though the pr ef etch operation uses the buffer as a cache, finding the requested data in
the buffer is a prefetch hit, not a cache operation hit.
To enable Prefetch, use Mode Select page 08h, byte 12, bit 5 (Disable Read Ahead - DRA bit). DRA bit = 0
enables prefetch.
The drive does not use the Max Prefetch field (bytes 8 and 9) or the Prefetch Ceiling field (bytes 10 and 11).
When prefetch (read look-ahead) is enabled (enabled by DRA = 0), the drive enables prefetch of contiguous
blocks from the disc when it senses that a prefetch hit will likely occur. The drive disables prefetch when it
decides that a prefetch hit is not likely to occur.
14Cheetah T10 SAS Product Manual, Rev. A
5.0Reliability specifications
The following reliability specifications assume correct host and drive operational interface, including all interface timings, power supply voltages, environmental requirements and drive mounting constraints.
Seek error rate:Less than 10 errors in 108 seeks
Read Error Rates
Recovered DataLess than 10 errors in 1012 bits transferred (OEM default settings)
Unrecovered DataLess than 1 sector in 1016 bits transferred
Miscorrected DataLess than 1 sector in 1021 bits transferred
Interface error rate:Less than 1 error in 1012 bits transferred
MTBF1,400,000 hours
Preventive maintenance:None required
1.Error rate specified with automatic retries and data correction with ECC enabled and all flaws reallocated.
1
5.1Error rates
The error rates stated in this manual assume the following:
• The drive is operated per this specification using DC power as defined in this manual (see Section 6.2).
• Errors caused by host system failures are excluded from error rate computations.
• Assume random data.
• Default OEM error recovery settings are applied. This includes AWRE, ARRE, full read retries, full write
retries and full retry time.
5.1.1Recoverable Errors
Recovereable errors are those detected and corrected by the drive, and do not require user intervention.
Recoverable Data errors will use correction, although ECC on-the-fly is not considered for purposes of recov-
ered error specifications.
Recovered Data error rate is determined using read bits transferred for recoverab le errors occurring during a
read, and using write bits transferred for recoverable errors occurring during a write.
5.1.2Unrecoverable Errors
Unrecoverable Data Errors (Sense Key = 03h) are specified at less than 1 sector in error per 1016 bits transferred. Unrecoverable Data Errors resulting from the same cause are treated as 1 error for that block.
Cheetah T10 SAS Product Manual, Rev. A15
5.1.3Seek errors
A seek error is defined as a failure of the drive to position the heads to the addressed track. After detecting an
initial seek error, the drive automatically performs an error recovery process. If the error recovery process fails,
a seek positioning error (Error code = 15h or 02h) will be reported with a Hardware error (04h) in the Sense
Key. Recoverable seek errors are specified at Less than 10 errors in 10
8
seeks. Unrecoverable seek errors
(Sense Key = 04h) are classified as drive failures.
5.1.4Interface errors
An interface error is defined as a failure of the receiver on a port to recover the data as transmitted by the
device port connected to the receiver. The error may be detected as a running disparity error, illegal code, loss
of word sync, or CRC error.
5.2Reliability and service
You can enhance the reliability of Cheetah disc drives by ensuring that the drive receives adequate cooling.
Section 6.0 provides temperature measurements and other information that may be used to enhance the service life of the drive. Section 8.2 provides recommended air-flow information.
5.2.1Mean time between failure (MTBF)
The production disc drive shall achieve a MTBF of 1,400,000 hours when operated in an environment that
ensures the HDA case temperatures specified in Section
the specification limits of the operating environment will not affect MTBF performance. Continual or sustained
operation at case temperatures above the values shown in Section
6.4 are not exceeded. Short-term excursions up to
6.4.1 may degrade product reliability.
The MTBF target is specified as device power-on hours (POH) for all drives in service per failure.
MTBF =Estimate power-on operating hours in the period
----------------------------------------------------------------Number of drive failures in the period
Estimated power-on operation hours means power-up hours per disc drive times the total number of disc
drives in service. Each disc drive shall have accumulated at least nine months of operation. Data shall be cal
culated on a rolling average base for a minimum period of six months.
MTBF is based on the following assumptions:
• 8,760 power-on hours per year.
• 250 average on/off cycles per year.
• Operations at nominal voltages.
• Systems will provide adequate cooling to ensure the case temperatures specified in Sectio n 6.4.1 are not
exceeded.
Drive failure means any stoppage or substandard performance caused by drive malfunction.
A S.M.A.R.T. predictive failure indicates that the drive is deteriorating to an imminent failure and is considered
an MTBF hit.
5.2.2Preventive maintenance
No routine scheduled preventive maintenance is required.
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16Cheetah T10 SAS Product Manual, Rev. A
5.2.3Hot plugging the drive
When a disc is powered on by switching the power or hot plugged, the drive runs a self test before attempting
to communicate on its’ interfaces. When the self test completes successfully, the drive initiates a Link Reset
starting with OOB. An attached device should respond to the link reset. If the link reset attempt fails, or any
time the drive looses sync, the drive initiated link reset. The drive will initiate link reset once per second but
alternates between port A and B. Therefore each port will attempt a link reset once per 2 seconds assuming
both ports are out of sync..
If the self-test fails, the does not respond to link reset on the failing port.
Note.It is the responsibility of the systems integrator to assure that no temperature, energy, voltage haz-
ard, or ESD potential hazard is presented during the hot connect/disconnect operation. Discharge
the static electricity from the drive carrier prior to inserting it into the system.
Caution. The drive motor must come to a complete stop prior to changing the plane of operation. This time is
required to insure data integrity.
5.2.4S.M.A.R.T.
S.M.A.R.T. is an acronym for Self-Monitoring Analysis and Reporting Technology. This technology is intended
to recognize conditions that indicate imminent drive failure and is designed to provide sufficient warning of a
failure to allow you to back up the data before an actual failure occurs.
Note.The drive’s firmware monitors specific attributes fo r degradation over time but can’t predict insta nta-
neous drive failures.
Each monitored attribute has been selected to monitor a specific set of failure conditions in the operating performance of the drive and the thresholds are optimized to minimize “false” and “failed” predictions.
Controlling S.M.A.R.T.
The operating mode of S.M.A.R.T. is controlled by the DEXCPT and PERF bits on the Informa tional Exceptions
Control mode page (1Ch). Use the DEXCPT bit to en able or disable the S.M.A.R.T. feature. Setting the DEX
CPT bit disables all S.M.A.R.T. functions. When enabled, S.M.A.R.T. collects on-line data as the drive performs
normal read and write operations. When the PERF bit is set, the drive is considered to be in “On-line Mode
Only” and will not perform off-line functions.
You can measure off-line attributes and force the drive to save the data by using the Rezero Unit command.
Forcing S.M.A.R.T. resets the timer so that the next scheduled interrupt is in two hours.
You can interrogate the drive through the host to determine the time remaining before the next scheduled mea surement and data logging process occurs. To accomplish this, issue a Log Sense command to log page 0x3E.
This allows you to control when S.M.A.R.T. interruptions occur. Forcing S.M.A.R.T. with the RTZ command
resets the timer.
Performance impact
S.M.A.R.T. attribute data is saved to the disc so that the events that caused a predictive failure can be recreated. The drive measures and saves paramete rs once every two hours subject to an idle period on the drive
interfaces. The process of measuring off-line attribute data and saving data to the disc is uninterruptable. The
maximum on-line only processing delay is summarized below:
Maximum processing delay
-
S.M.A.R.T. delay times
On-line only delay
DEXCPT = 0, PERF = 1
42 milliseconds
Fully-enabled delay
DEXCPT = 0, PERF = 0
163 milliseconds
Cheetah T10 SAS Product Manual, Rev. A17
Reporting control
Reporting is controlled by the MRIE bits in the Informational Exceptions Control mode page (1Ch). Subject to
the reporting method, the firmware will issue to the host an 01-5Dxx sense code. The error code is preserved
through bus resets and power cycles.
Determining rate
S.M.A.R.T. monitors the rate at which errors occur and signals a predictive failure if the ra te of d eg raded erro rs
increases to an unacceptable level. To determine rate, error events are logged and compare d to the num ber of
total operations for a given attribute. The interval defines the nu mber of oper ations o ver whic h to me asure the
rate. The counter that keeps track of the current number of operations is referred to as the Interval Counter.
S.M.A.R.T. measures error rates. All errors for each monitored attribute are recorded. A counter ke eps track of
the number of errors for the current interval. This counter is referred to as the Failure Counter.
Error rate is the number of errors per operation. The algori thm that S.M.A.R.T. uses to record rates of error is to
set thresholds for the number of errors and their interval. If the number of errors exceeds the threshold before
the interval expires, the error rate is considered to be unacceptable. If the number of errors does not exceed
the threshold before the interval expires, the error rate is considered to be acceptable. In either case, the inter
val and failure counters are reset and the process starts over.
Predictive failures
S.M.A.R.T. signals predictive failures when the drive is performing unacceptably for a period of time. The firmware keeps a running count of the number of times the error rate for each attribute is unacceptable. To accomplish this, a counter is incremented e ach time the erro r rate is unacceptable and decremented (not to exceed
zero) whenever the error rate is acceptable. If the counter continually increments such that it reaches the pre
dictive threshold, a predictive failure is signaled. This counter is referred to as the Failure History Counter.
There is a separate Failure History Counter for each attribute.
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5.2.5Thermal monitor
Cheetah drives implement a temperature warning system which:
1. Signals the host if the temperature exceeds a value which would threaten the drive.
2. Signals the host if the temperature exceeds a user-specified value.
3. Saves a S.M.A.R.T. data frame on the drive which exceeds the threatening temperature value .
A temperature sensor monitors the drive temperature and issues a warning over the interface when the temperature exceeds a set th reshold. The t emperature is measured a t power-up an d then at te n-minute interv als
after power-up.
The thermal monitor system generates a warning code of 01-0B01 when the temperature exceeds the specified limit in compliance with the SCSI standard. The drive temperature is reported in the FRU code field of
mode sense data. You can use this information to determine if the warning is due to the temperature exceeding
the drive threatening temperature or the user-specified temperature.
This feature is controlled by the Enable Warning (EWasc) bit, and the reporting mechanism is controlled by the
Method of Reporting Informational Exceptions field (MRIE) on the Informational Exceptions Control (IEC)
mode page (1Ch).
The current algorithm implem ents two temperature trip points. The first trip point is set at 68°C which is the
maximum temperature limit according to the drive specification. The second trip point is user-selectable using
the Log Select command. The reference temperature parameter in the temperature log page (see Table
1) can
18Cheetah T10 SAS Product Manual, Rev. A
be used to set this trip point. The default value for this drive is 68°C, however, you can set it to any value in the
range of 0 to 68°C. If you specify a temperature greater than 68°C in this field, the temperature is rounded
down to 68°C. A sense code is sent to the host to indicate the rounding of the parameter field.
Table 1: Temperature Log Page (0Dh)
Parameter CodeDescription
0000h
0001h
Primary Temperature
Reference Temperature
5.2.6Drive Self Test (DST)
Drive Self Test (DST) is a technology designed to recognize drive fault conditions that qualify the drive as a
failed unit. DST validates the functionality of the drive at a system level.
There are two test coverage options implemented in DST:
1. Extended test
2. Short text
The most thorough option is the extended test that performs var io us t es ts on the driv e a nd sca n s ev er y lo gical
block address (LBA) of the drive. The short test is time-restricted and limited in length—it does not scan the
entire media surface, but does some fundamental tests and scans portions of the media.
If DST encounters an error during either of these tests, it reports a fault condition. If the drive fails the test,
remove it from service and return it to Seagate for service.
5.2.6.1DST failure definition
The drive will present a “diagnostic failed” condition through the self-tests results value of the diagnostic log
page if a functional failure is encountered during DST. The channel and servo parameters are not modified to
test the drive more stringently, and the number of retries are not reduced. All retries and recovery processes
are enabled during the test. If data is recoverable, no failure condition will be reported regardless of the number
of retries required to recover the data.
The following conditions are considered DST failure conditions:
• Seek error after retries are exhausted
• Track-follow error after retries are exhausted
• Read error after retries are exhausted
• Write error after retries are exhausted
Recovered errors will not be reported as diagnostic failures.
5.2.6.2Implementation
This section provides all of the information necessary to implement the DST function on this drive.
Cheetah T10 SAS Product Manual, Rev. A19
5.2.6.2.1State of the drive prior to testing
The drive must be in a ready state before issuing the Send Diagnostic command. There are multiple reasons
why a drive may not be ready, some of which are valid conditions, and not errors. For example, a drive may be
in process of doing a format, or another DST. It is the responsibility of the host application to determine the “not
ready” cause.
While not technically part of DST, a Not Ready condition also qualifies the drive to be returned to Seagate as a
failed drive.
A Drive Not Ready condition is reported by the drive under the following conditions:
• Motor will not spin
• Motor will not lock to speed
• Servo will not lock on track
• Drive cannot read configuration tables from the disc
In these conditions, the drive responds to a Test Unit Ready command with an 02/04/00 or 02/04/03 code.
5.2.6.2.2Invoking DST
To invoke DST, submit the Send Diagnostic command with the appropriate Function Code (001b for the short
test or 010b for the extended test) in bytes 1, bits 5, 6, and 7.
5.2.6.2.3Short and extended tests
DST has two testing options:
1. short
2. extended
These testing options are described in the following two subsections.
Each test consists of three segments: an electrical test segment, a servo test segment, and a read/ve rify s can
segment.
Short test (Function Code: 001b)
The purpose of the short test is to provide a time-limited test that tests as much of the drive as possible within
120 seconds. The short test does not scan the entire media surface, but does some fundamental tests and
scans portions of the media. A complete read/verify scan is not performed and only factual failures will report a
fault condition. This option provides a quick confidence test of the drive.
Extended test (Function Code: 010b)
The objective of the extended test option is to empirically test critical drive componen ts. For example, the seek
tests and on-track operations test the positioning mechanism. The read operation tests the read head element
and the media surface. The write element is tested through read/write/read operations. The integrity of the
media is checked through a read/verify scan of the media. Motor functionality is tested by default as a part of
these tests.
The anticipated length of the Extended test is reported through the Control Mode page.
5.2.6.2.4Log page entries
When the drive begins DST, it creates a new entry in the Self-test Results Log page. The new entry is created
by inserting a new self-test parameter block at the b eginning of the self- test result s log parame ter section of the
log page. Existing data will be moved to make room for the new parameter block. The drive reports 20 param
eter blocks in the log page. If there are more than 20 parameter blocks, the least recent parameter block will be
deleted. The new parameter block will be initialized as follows:
1. The Function Code field is set to the same value as sent in the DST command
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20Cheetah T10 SAS Product Manual, Rev. A
2. The Self-Test Results Va lue field is set to Fh
3. The drive will store the log page to non-volatile memory
After a self-test is complete or has been aborted, the drive updates the Self-Test Results Value field in its Self-
Test Results Log page in non-volatile memory. The host may use Log Sense to read the results from up to the
last 20 self-tests performed by the drive. Th e se lf- te st r esults value is a 4-bit field that reports the results of the
test. If the field is set to zero, the drive passed with no errors detected by the DST. If the field is not set to zero,
the test failed for the reason reported in the field.
The drive will report the failure condition and LBA (if applicable) in the Self-test Results Log parameter. The
Sense key, ASC, ASCQ, and FRU are used to report the failure condition.
5.2.6.2.5Abort
There are several ways to abort a diagnostic. You can use a SCSI Bus Reset or a Bus Device Reset message
to abort the diagnostic.
You can abort a DST executing in background mode by using the abort code in the DST Function Code field.
This will cause a 01 (self-test aborted by the application client) code to appear in the self-test results values
log. All other abort mechanisms will be reported as a 02 (self-test routine was interrupted by a reset condition).
5.2.7Product warranty
Beginning on the date of shipment to the customer and continuing for the period specified in your purchase
contract, Seagate warrants that each product (including components and subassemblies) that fails to function
properly under normal use due to defect in materia ls or workmanshi p or due to noncon formance to the applica
ble specifications will be repaired or replaced, at Seagate’s option and at no charge to the customer , if returned
by customer at customer’s expense to Seagate’s designated facility in accordance with Seagate’s warranty
procedure. Seagate will pay for transporting the repair or replacement item to the customer. For more detailed
warranty information, refer to the standard terms and conditions of purchase for Seagate products on your pur
chase documentation.
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The remaining warranty for a particular drive can be determined by calling Seagate Customer Service at
1-800-468-3472. You can also determine remaining warranty using the Seagate web site (www.seagate.com).
The drive serial number is required to determine remaining warranty information.
Shipping
When transporting or shipping a drive, use only a Seagate-approved container. Keep your original box.
Seagate approved containers are easily identified by the Se agat e Ap pr oved Package la be l. Shipp ing a drive in
a non-approved container voids the drive warranty.
Seagate repair centers may refuse receipt of components improperly packaged or obviously damaged in transit. Contact your authorized Seagate distributor to purchase additi onal boxes. S eagate recommends shipping
by an air-ride carrier experienced in handling computer equipment.
Product repair and return information
Seagate customer service centers are the only facilities authorized to service Seagate drives. Seagate does
not sanction any third-party repair facilities. Any unauthorized repair or tampering with the factory seal voids
the warranty.
Cheetah T10 SAS Product Manual, Rev. A21
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