Seagate, Seagate Technology and the Wave logo are registered trademarks of Seagate Technology LLC
in the United States and/or other countries. Cheetah, SeaTools and SeaTDD are either trademarks or registered trademarks of Seagate Technology LLC or one of its affiliated companies in the United States and/
or other countries. All other trademarks or registered trademarks are the property of their respective owners.
One gigabyte, or GB, equals one billion bytes when referring to hard drive capacity. Accessible capacity
may vary depending on operating environment and formatting. Quantitative usage examples for various
applications are for illustrative purposes. Actual quantities will vary based on various factors, including file
size, file format, features and application software. Seagate reserves the right to change, without notice,
product offerings or specifications.
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 15K.5 and other
Seagate SAS drives.
Figure 1. Cheetah 15K.5 SAS disc drive
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Cheetah 15K.5 SAS Product Manual, Rev. E
Cheetah 15K.5 SAS Product Manual, Rev. E
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2.0Standards, compliance and reference documents
The drive has been d evelope d as a system p eriphe ral to the hig hest st and ards of desig n and constru c tion. 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 the
areas of safety, power distribution, shielding, audible noise control, and temperature regulation. In particular,
the drive must be securely mounted to guarantee the specified performance characteristics. Mounting by bottom 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 driv e is a UL recognize d compo nent per UL 1950 , CSA certifi ed to CAN /CSA C22.2 N o. 95 095, and VDE or TUV certified to 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 subassembly and is not subject to Subpart B of Part 15 of the FCC Rules and
Regulations nor the Radio Interference Regulations 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 cables are external to the enclosure,
shielded cables should be used, with the shields grounded to the enclosure and to the host controller.
2.1.1.1Electromagn etic susc ept ibili ty
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 2, 3 and 4, for DC power requirements.
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Cheetah 15K.5 SAS Product Manual, Rev. E
2.2Compliance
2.2.1Electromagn etic complia nce
Seagate uses an independent laboratory to confirm compliance with the directives/standards for CE Marking
and C-Tick Marking. T he dr ive was tested in a r epre sent ative system for typica l applications. The select ed system 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 th is Seag ate mo del comp lies with the dir ectives/st and ards, we cannot gu aran tee
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 Management Agency (SMA).
Korean MIC
If this model has the Korean Min ist ry of Infor mat ion and Com munication (MIC) logo, it complie s with par agr aph
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 number, 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 Inspection (BSMI).
2.3European Uni on Restric tion of Hazardous Substances (RoHS)
The European U nion Restr icti on of Hazard ous S ubst ance s (RoHS ) Dire cti ve re strict s the p resen ce of ch emic al
substances, including Lead (Pb), in electronic products effective July 2006.
A number of parts and materials in Seagate products are procured from external suppliers. We rely on the representations of our suppliers regarding the presence of RoHS substances in these parts and materials. Our
supplier contracts require compliance with our chemical substance restrictions, and our suppliers document
their compliance wi th our re quire ment s by providing material conte nt declar ations for al l par ts an d mater ial s for
the disc drives documented in this publication. Current supplier declarations include disclosure of the inclusion
of any RoHS-regulated substance in such parts or materials.
Cheetah 15K.5 SAS Product Manual, Rev. E
5
Seagate also has internal system s in place to en sure ongoing complian ce with the RoHS Directive and all laws
and regulations which restrict chemical conte nt in electron ic produ cts. T hese system s include sta ndar d operating procedures that ensure that restricted substances are not utilized in our manufacturing operations, laboratory analytical validation testing, and an internal auditing process to ensure that all standard operating
procedures are complied with.
2.4Reference documents
Cheetah 15K.5 SAS Installation GuideSeagate part number: 100384785
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) Standard (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.
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Cheetah 15K.5 SAS Product Manual, Rev. E
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3.0General description
Cheetah drive s combin e Tunneling Ma gneto resistive (T M R) head s and a Ser ial Attached SCSI (SAS) interface
to provide high pe rfor mance , high cap acity d at a sto rage for a va riety o f system s includ ing en gineer ing workstations, network servers, mainframes, and supercomputers. The Serial Attached SCSI interface is designed to
meet next-generation 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 connectors, cables and electrical interface are compatible with Serial ATA (SATA), giving future users the choice of
populating their syste ms with eithe r S AS or SATA har d d isc dr ives. This allo ws you to continue to levera ge yo ur
existing investment in SCSI while gaining a 3Gb/s serial data transfer rate.
The head and disc assembly (HDA) is sealed at the factory. A ir 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 de dicated landing zone a t the innermost radius of the media to e liminate the p ossibility of
destroying or de grad i ng d at a b y l and ing in the data zone. Th e h eads autom atical ly go t o 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.
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Cheetah 15K.5 SAS Product Manual, Rev. E
3.1Standard featu re s
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 desc ription
The media used on the drive has an aluminum substrate coated with a thin film magnetic material, overcoated
with a proprietary protective layer for improved durability and environmental protection.
3.3Performance
• Firmware-controlled multisegmented cache designed to dynamically adjust segments for enhanced system
performance.
• 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 ca pacities
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 certain 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 used at the maximum available capacity at a given block size, but the excess
capacity above the guaranteed level will vary between other drive families and from generation to generation, 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 forward 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 cap acity to the value in the Nu mber of Blocks field. A value gre ater t han th e maxim um nu mbe r of
LBAs is rounded down to the maximum capacity.
3.7Factory -installed acce ssories
OEM standard drives are shipped with the Cheetah 15K.5 SAS Installation Guide, part number 100384785,
and the Safety and Regulatory Agency Specifications, part number 75789512 (unless otherwise specified).
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Cheetah 15K.5 SAS Product Manual, Rev. E
3.8Options (factory installed)
Yo u may order the following items which are incorporated at the manufacturing facility d uring 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 protection
against transit damage. U nit s shipped individually require add itional pro tection as pr ovided by th e singl e unit
shipping pack. Users planning single unit distribution should specify this option.
• The Cheetah 15K.5 SAS Installation Guide, part number 100384785, 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-ins talle d accessorie s
The following accessories are available. All kits may be installed in the field.
• Single-unit shipping pack.
Cheetah 15K.5 SAS Product Manual, Rev. E
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4.0Performance characteristics
This section provides detailed information concerning performance-related characteristics and features of
Cheetah drives.
4.1Internal drive characteristics
ST3300655SS ST3146855SS ST373455SS
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 inch890890890KBPI
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 stro keTypical6.87.5
1, 2
(msec)
1.Typical access times are measured under nominal conditions of temperature, voltage, and
horizontal orientation as measured on a representative sample of drives.
2.Access to data = access time + latency time.
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Cheetah 15K.5 SAS Product Manual, Rev. E
4.2.2Format command execution time (minutes)
ST3300655SSST3146855SSST373455SS
Maximum (wi th verify)
Maximum (without verify)
1209060
604530
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*:
Minimum73 Mbytes/sec
Maximum125 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, and 528 kbytes.
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 ) pri mitive, the drive waits for a S TART STOP UNIT com mand wi th th e 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 S PINUP) 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.
Cheetah 15K.5 SAS Product Manual, Rev. E
13
The START ST OP UN IT comm and m ay be used to comm and the dr ive to st op the spi ndle. Stop time is 30 seconds (maximum) from removal of DC power. There is no power control switch on the drive.
4.4Prefetc h / m ulti-segmen te d ca ch e 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 values 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 operation, 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 9.3.2.1.
4.5Cache operation
Note.Refer to the SAS Interface Manual for more detail concerning the cache bits.
Of the 16 Mbytes physical buffer sp ace 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 ), data requested by the host w ith a rea d comm and
is retrieved from the buf fe r, if possible, before any disc access is initiated . If cach e oper ation is not en abled, 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 i t. The retrieved data merely passes through some buf fer
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.
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, refer to section 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 capability 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 15K.5 SAS Product Manual, Rev. E
4.5.1Caching write data
Write caching is a write operation by the drive that makes use of a drive buffer storage area where the data 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 dat a logical blo cks excee d the size o f the segm ent b eing wr itten into, wh en th e en d of the
segment is reached, the data is written i nto the b eginning of the same cache segment, overwriting the dat a 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 generated.
The Synchronize Ca che command may be used to force the drive to write all cached wri te dat a to the med ium.
Upon completion of a Synchronize Cache command, all data received from previous write commands will have
been written to the medium.
Table 9.3.2.1 shows the mode default settings for the drive.
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 prefetch 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.
Cheetah 15K.5 SAS Product Manual, Rev. E
15
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.
5.1Error rate s
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.
1
5.1.1Recoverable Errors
Recoverable errors are those detected and corrected by the drive, and do not require user intervention.
Recoverable Data errors will use correction, although ECC o n-the-fly is not considered fo r purposes o f recov-
ered error specifications.
Recovered Data error rate is determined using read bits transferred for recoverable 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.
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Cheetah 15K.5 SAS Product Manual, Rev. E
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 automaticall y perf orms an error recovery process. If the error recover y 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 108 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 6.4 are not exceeded. Short-term excursions up to
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 6.4.1 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 calculated 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 Section 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 mainte nan ce
No routine scheduled preventive maintenance is required.
Cheetah 15K.5 SAS Product Manual, Rev. E
17
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 m ust come to a com pl ete s top pr ior to ch angi ng the pla ne of o pera ti on. T his time i s
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 f irmwar e m onitor s speci fic attr ibutes for degradation ove r tim e b ut can ’ t pr edict in sta nt a-
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” predi ctions.
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 Informational Exce ptions
Control mode page (1Ch). Use the DEXCPT bit to enable or disable the S.M.A.R.T. feature. Setting the DEXCPT bit disables all S.M.A.R.T. functions. When enab led, S .M. A.R.T. collects on -line d ata as the drive p erfor ms
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 th e host t o dete rmine the time remaining b efore the ne xt schedu l ed me asurement and d at a logg i ng p rocess occur s . To accomplish this, i ssue 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 parameters 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
DEXCP T = 0, PE R F = 0
163 milliseconds
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Cheetah 15K.5 SAS Product Manual, Rev. E
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 si gna ls a predi ctive fai lure if the rat e of degrad ed err ors
increases to an unacceptabl e level. To determine rate, error events are logged and com pa red to the num ber of
total operations for a given attribute. The interval defines the number of operations over which to measure 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 keeps 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 oper ation. The algori thm tha t S .M.A.R .T. uses to record rate s of err or i s 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 interval 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 each time the error 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 predictive 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.
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 threshold. The temperature is measured at power-up and then at ten-minute intervals
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 dat a. You can use this infor matio n to deter mine if the warning i s due to t he tem per atur e excee ding
the drive threatening temperature or the user-specified temperature.
This feature is controlled by the En able W a rni ng (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 implements 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 re feren ce tempe ratur e p aram eter in the tempera ture log page (see Table 1) can
Cheetah 15K.5 SAS Product Manual, Rev. E
19
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 various tests on the drive and scans every logical
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 fa ilure 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.
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Cheetah 15K.5 SAS Product Manual, Rev. E
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 conditio ns, and not erro rs. For example, a drive may be
in process of doing a form at, or anothe r D ST. It is the responsibility o f the ho st applic atio n to det erm ine 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/verify scan
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 rea d/ver ify scan is not per formed and onl y factu al failu res 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 components. 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-te st parameter block a t the beginning of t he se lf-test results log p a ram eter section of the
log page. Existing data will be moved to make room for the new parameter block. The drive reports 20 parameter blocks in the log p ag e. If th ere are more than 20 p ar amet er blocks, the least r ecent p a rame ter 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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