Seagate , Seagate Technology, and the Seagate logo are registered trademarks of Seagate T echnology, LLC. Cheetah, Sea FAX, SeaFONE, SeaBOARD, and SeaTDD are either trademarks or
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Printed in the United States of America
Revision status summary sheet
RevisionDateWriter/EngineerSheets Affected
A7/26/2000L. Newman/G. Velaski1/1, v thru viii, 1 thru 72.
B (Class A Release) 8/24/2000L. Newman/G. V elaskiPage 10.
C8/29/2000L. Newman/G. VelaskiPages 6, 9, 10, 41, 42, 43, 47, 48, 52,
This manual describes Seagate Technology®, LLC, Cheetah 36LP FC (Fibre Channel) disc drives.
Cheetah 36LP FC dr i ves support the Fibr e Cha nnel Arb itrated Loop and SCSI Fibre Cha nne l P r otoc ol s pec i fi-
cations to the extent describe d in this manual. The Fibre Channel In terface Manual (part number 77767496)
describes the ge neral Fibre Chan nel Arbitrated Loop character istics of t his and othe r Seagate Fibre Channel
drives.
Figure 1.
Cheetah 36LP FC
family disc drive
2Cheetah 36LP FC Product Manual, Rev. C
Cheetah 36LP FC Product Manual, Rev. C3
2.0Applicable standards and reference documentation
The drive has been developed as a system peripheral to the highest standards of design and construction. The
drive depends upon i ts host equip ment to provide adequ ate power and environment i n order to achieve optimum performance and compli ance with applicable industry and governm ental 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 secur e ly mo unte d i n o rd er to guarantee the specified perfor ma nc e char acteristics. Mounting by bottom holes must meet the requirements of Section 8.5.
2.1Standards
The Cheetah 36LP FC family com plies with Seagate standards as not ed in the appropriate sectio ns of this
manual and the Seagate Fibre Channel Interface Manual, part number 77767496.
The Cheetah 36LP FC disc drive is a UL recognized component per UL1950, CSA certified to CAN/CSA C22.2
No. 950-95, 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.
As such the drive is suppli ed as a subassembly and is not su bject to Subpar t 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. As such, 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 req uirements in their syst em. Shielded I/O
cables may be required if the e nclosure does not provide ad equate sh ielding. If the I/O c ables are externa l to
the enclosure, shielded cables should be used, with the shields grounded to the enclosure and to the host controller.
2.1.1.1Electromagnetic susceptibility
As a component assembly, the drive is not required to meet any susceptibility per formance requ irements. It is
the responsibility of tho se integrating the dr ive within their sy stem s to perform thos e tests req uired and design
their system to ensu re that equipment operating in the sam e system as the drive or external to the s ystem
does not adversely affect the performance of the drive. See Section 5.1.1 and T able 1, DC power requirements.
2.1.2Electromagnetic compliance
Seagate uses an indep endent laborator y to confir m compliance wi th the directives/standar ds for CE Marking
and C-Tick Marking. The drive was tested in a representative system for typical applications. The selected 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 this Seagate model complies with the directives/standards, we cannot guarantee
that all systems will comply. The computer manufacturer or system i ntegrator shall confir m EMC complianc e
and provide the appropriate marking for their product.
Electromagnetic compliance for the European Union
If this model has the CE Marki ng it complies with the European Union requirem ents of the Electromagnetic
Compatibility Direc tive 89/336/EEC o f 03 May 1989 as ame nded by Direct ive 92/31/EE C of 28 Ap r il 1992 an d
Directive 93/68/EEC of 22 July 1993.
4Cheetah 36LP FC Product Manual, Rev. C
Australian C-Tick
If this model has the C-Tick Markin g it complies with the Australia/New Zea land Standard A S/NZS3548 199 5
and meets the Electro magnetic Compatibility (EMC) Framework requirements of Australia’s Spectrum Management Agency (SMA).
2.2Reference documents
Cheetah 36LP FC Installation Guide
Seagate part number: 83329481
Fibre Channel Interface Manual
Seagate part number: 77767496
ANSI Fibre Channel Documents
X3.230-1994FC Physical and Signaling Interface (FC-PH)
X3.297.1997FC-PH-2 Fibre Channel Physical and Signaling Interface-2
X3.303.1998FC-PH-3 Fibre Channel Physical and Signaling Interface-3
X3.272-1996FC Arbitrated Loop (FC-AL)
X3.269-1996Fibre Channel Protocol for SCSI (FCP)
NCITS TR-19Private Loop SCSI Direct Attach (PLDA)
NCITS TR-20Fabric Loop Attachment (FC-FLA)
SFF-8045 Specification for 40-pin SCA-2 Connector with Parallel Selection
SFF-8067 Specification for 40-pin SCA-2 Connector with Bidirectional Enclosure Services
Interface
ANSI Small Computer System Interface (SCSI) Documents
X3.131-1994(SCSI-2)
X3.270-1996(SCSI-3) Architecture Model
NCITS 305-199X(SCSI-3) Enclosure Services
30553-001Specification for Acoustic Test Requirement and Procedures
In case of conflict between this document and any referenced document, this document takes precedence.
Cheetah 36LP FC Product Manual, Rev. C5
3.0General description
CheetahTM 36LP FC drives combine giant magnet oresistive (GMR) heads, partial resp onse/maximum likelihood (PRML) read channel ele ctronic s, embedded servo technology, and a Fibre Channel interface to provide
high performance, high capaci ty data storage for a variety of syste ms incl uding en ginee ring work statio ns, network servers, mainframes, and supercomputers.
Cheetah 36LP FC drives are random access storage devices designed to support the Fibre Channel Arbitrated
Loop (FC-AL) and SCSI Fibre Channe l Protocol as describe d in the ANSI specificatio ns, this document, and
the Fibre Channel Interface Manual (part number 77767496) which describes the general interface characteristics of this dr i ve. Cheetah 36LP FC drives are clas sifie d as in tel li gen t p eripherals and pr ovide level 2 conformance (highest level) with the ANSI SCSI-1 standard.
The head and disc as sembly (HDA) is sealed at the factory. Air recirculates withi n the HDA through a nonreplaceable filter to maintain a contamination-free HDA environment.
See Figure 2 for an exploded view of the drive. Never disassemble the HDA. This exploded view is for information only. Do not attempt to service items in the sealed enclosure (heads, media, actuator, etc.) as this requires
special facilities. The drive conta ins no parts replace able by the user and openin g the HDA for any reason
voids your warranty.
Figure 2.Cheetah 36LP FC disc drive
Cheetah 36LP FC drives use a dedicated land ing zone at the innermost radius of the media to eliminate the
possibility of destroying or degrading data by landing in the data 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 handl ing. The shipping lock disengages and the head lo ad process begins when power is
applied to the drive.
Cheetah 36LP FC 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.
6Cheetah 36LP FC Product Manual, Rev. C
3.1Standard features
Cheetah 36LP FC drives have the following standard features:
• Integrated dual port FC-AL controller
• Concurrent dual port transfers
• Support for FC arbitrated loop, private and public attachment
• Differential copper FC drivers and receivers
• Downloadable firmware using the FC-AL interface
• Supports SCSI enclosure services via interface connector
• 128-deep task set (queue)
• Supports up to 32 initiators
• Drive selection ID and configuration options are set on the FC-AL backpanel or through interface com-
mands. Jumpers are not used on the drive.
• Fibre Channel worldwide name uniquely identifies the drive and each port
• User-selectable logical block size (512 to 704 bytes per logical block)
• Selectable frame sizes from 128 to 2,112 bytes
• Industry standard 3.5-inch low profile form factor dimensions
• Programmable logical block reallocation scheme
• Flawed logical block reallocation at format time
• Programmable auto write and read reallocation
• Reed-Solomon error correction code
• Sealed head and disc assembly (HDA)
• No preventive maintenance or adjustments required
• Dedicated head landing zone
• Automatic shipping lock
• Embedded Grey Code track address to eliminate seek errors
• Self-diagnostics performed at power on
• 1:1 interleave
• Zone bit recording (ZBR)
• Vertical, horizontal, or top down mounting
• Dynamic spindle brake
• 4,096 Kbyte data buffer (16,384 Kbytes on FCV drives). See Section 4.5.
• Embedded servo design
• Reallocation of defects on command (Post Format)
The media used on the dr ive has a di ameter of a pproximately 84 mm (approximate ly 3.3 inch es). The aluminum substrate is coate d with a thin film magnet ic material, overcoated wi th a proprietar y protective layer for
improved durability and environmental protection.
3.3Performance
• Programmable multi-segmentable cache buffer
• 106 Mbytes/sec maximum instantaneous data transfers per port (212 Mbytes/sec with 2 GHz link rate)
• Self-Monitoring Analysis and Reporting Technology (S.M.A.R.T.)
• Dithering
3.5Unformatted and formatted capacities
Formatted capacity depends on the spare reallocation sectors scheme selected, the number of data tracks per
sparing zone, and the number of alternate sectors (LB As) per sparing zone. The following table shows the
standard OEM model capacity:
Standard OEM models are formatted to 512 bytes per block. You can order other capacities by requesting a different sparing scheme and logical block size.
The sector size is selectable at format time. Users having the necessary equipment may modify the data block
size before issuing a format com mand and obtain different formatted capacities than those listed. Cheetah
36LP FC drives use a zone spari ng sche me. The drive is divide d into frequen cy zones with a variable number
of spares in each zone.
Note.
For 2 gigabit operation, sector sizes must be divisible by 8.
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 Fibre Channel Interface Manual, par t number 7767 496. A value of
zero in the Number of Blocks field indica tes that the dr ive will not change the ca pacity it is curren tly formatted
to have. A number other than zero and less than the maximum number of LBAs in th e Number of Bl ocks field
changes the total dr ive capacity to the value in th e Num ber of Bl ocks field. A value greater tha n the ma ximum
number of LBAs is rounded down to the maximum capacity.
3.7Factory-installed accesso r ies
OEM standard drives are shipped with the Cheetah 36LP FC Installation Guide (part number 83329481).
3.8Factory-installed options
You may order the following items which are incorporated at the m anufacturing facility durin g 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 nor mally shipped in bulk packaging to provide maxi mum protection
against transit damage. Units shipped individually require additional protection as provided by the single unit
shipping pack. Users planning single unit distribution should specify this option.
• The Ch eetah 36LP FC Installation Gui de, part number 833294 81, is usually included with e ach standard
OEM drive shipped, but extra copies may be ordered.
• The Safety and Regulat ory Agency Specifications, pa rt number 75789512, is usua lly included with each
standard OEM drive shipped, but extra copies may be ordered.
3.9User-installed accessories
The following accessories are available. All kits may be installed in the field.
• Evaluation kit, part number 73473641.
This kit provides an adapte r car d (“T-card ”) to a llow cable connec tions for two FC ports and DC p ower. Two
twin axial cables, 6 feet in length, are included for the input and output connections to the FC interface.
• Single-unit shipping pack.
8Cheetah 36LP FC Product Manual, Rev. C
Cheetah 36LP FC Product Manual, Rev. C9
4.0Performance characteristics
This section provides detailed information concerning performance-related characteristics and features of
Cheetah 36LP FC drives.
4.1Internal drive characteristics
ST336704FC/FCVST318304FC/FCV
Drive capacity36.7 ..........................18.35................................Gbytes (formatted, rounded off value)
Read/write data heads12 .............................6
Bytes per track215,248 ....................215,248............................Bytes (average, rounded off values)
Bytes per surface3,035 ........................3,035................................Mbytes (unformatted, rounded off value)
Tracks per surface (total)14,100 ......................14,100..............................Tracks (user accessible)
Tracks per inch18,145 ......................18,145..............................TPI
Peak bits per inch334 ...........................334...................................KBPI
Internal data rate280-427....................280-427............................Mbits/sec (variable with zone)
Disc rotation speed10,025 ......................10,025..............................r p m (+
Fibre Channel Interface maximum instantaneous transfer rate1 GHz
106 Mbytes/sec* per
port (dual port = 212
Mbytes/sec*)
Logical block sizes
Default is 512-byte data blocks
Variable 512 to 704 bytes per sector in even number of byte s per sector. If n (number of bytes per sector) is odd, then n-1 will be used.
Read/write consecutive sectors on a track
Flaw reallocation performance impact (f or flaws reallocated at format time
using the spare sectors per sparing zone reallocation scheme.)
Overhead time for head switch in sequential mode
Overhead time for one track cylinder switch in sequential mode
Average rotational latency
*Assumes no errors and no relocated logical blocks. Rate measured from the start of the first logical block transfer to or
from the host.
Yes
Negligible
0.8 msec
1.2 msec (typical)
2.99 msec
2 GHz
212 Mbytes/sec* per
port (dual port = 424
Mbytes/sec*)
4.3Start/stop time
If the Motor Start option is disabled, the drive becomes ready within 20 seconds after DC power is applied. If a
recoverable error condition is detected during the start sequence, the drive executes a recovery procedure and
the time to become ready may exceed 30 seconds. Stop time is less than 30 seconds (maximum) from removal
of DC power.
If the Motor Star t option is enabled, the i nternal contr oller accepts th e commands list ed in the Fibre ChannelInterface Manual less than 3 seconds after DC power has been applied. After the Moto r Start co mmand has
been received, the drive becomes ready for normal operations within 20 seconds (excluding the error recovery
procedure). The Motor Start command can also be used to command the drive to stop the spindle.
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 con trol algorithms that in many
cases can enhance s ystem 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 pro per values in
the applicable bytes in page 08h. Prefetch and cache operations are indep end ent features from the sta ndp oin t
that each is en abled and disabled ind ependently us ing the Mode Select comm and; 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 pa rameter values (Mode Page 08h) for standard OEM versions of this
drive family are given in Table 16.
Cheetah 36LP FC Product Manual, Rev. C11
4.5Cache operation
Note.
Of the 4,096 kbytes physical buffer space i n the drive, 3,600 kbytes (14,399 k bytes of the 16,384 kbytes on
FCV units) can be used as a cache.
The buffer can be divided into logical segments (using Mode Select Page 08h, byte 13) 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 Fibr e Ch ann el I nter face Manual), d ata re ques te d by the h ost with a r ea d
command is retr ieved from the buffer, if possible, before any disc access is initia ted. If ca che operation is not
enabled, the buffer (still segmented with the required number of segm ents) is still used, but only a s 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 thr ou gh some buffer segment on the way to the host. On a ca ch e
miss, all data transfers to the host are in accordance with buffer-full ratio rules. On a cache hit, the drive ignores
the buffer-full ratio rules. See the explanation provided with the information about Mode Page 02h (disconnect/
reconnect control) in the Fibre Channel Interface Manual.
The following is a simplified description of the prefetch/cache operation:
Case A
1. Drive transfers to the initiator the first logical block requested plus all subsequent contiguous logical blocks
2. When a requested logica l block is reached that is not in any cache seg ment, the drive fetches it and any
3. If the prefetch feature is enabled, refer to section 4.5.2 for operation from this point.
Refer to the Fibre Channel Interface Manual for more detail concerning the cache bits.
—read command is received and the first logical block is already in the cache:
that are already in the cache. This data may be in multiple segments.
remaining requested logical block addresses fr om the disc and pu ts them in a se gment of the ca che. The
drive transfers the remaining requested log ical blocks from the cache to the host in accordance with the
Mode Select Disconnect/Reconnect parameters, page 02h.
Case B
1. The drive fetches the requested logic al blocks from the disc and transfers them into a segment, and the n
2. If the prefetch feature is enabled, refer to section 4.5.2 for operation from this point.
During a prefetch, the drive crosses a cylinde r boundary to fetch data only if the Discontinuit y (DISC) bi t is set
to 1 in bit 4 of byte 2 of the Mode Select parameters page 08h. Default is zero for bit 4.
Each cache segment is actually a self-contained circ ular buffer whose length is an integer number of logical
blocks. The wrap-around capability of the individual segments greatly enhances the cache’s overall performance, allowing a wide range of user-selectable configu rations. The drive supports operation of any inte ger
number of segments from 1 to 16. Div ide th e 3,600 K bytes in the buffer by the number of se gments to get th e
segment size. Default is 3 segments.
Note.
4.5.1Caching write data
Write caching is a wr ite op eration by the dr ive that makes use of a drive buffer storage area where the data t o
be written to the medium is stored whil e the drive p erforms 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 s ame buffer space and segme ntat ion is u sed a s set up for read func tions.
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
—A Read command requests data, and the first logical block is not in any segment of the cache:
from there to the host in accordance with the Mode Select Disconnect/Reconnect parameters, page 02h.
The size of each segment is not repo r ted by Mode Sense c ommand pa ge 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 Selec t co mmand (bytes 14 a nd 15) does not set up a new seg ment s ize. 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.
12Cheetah 36LP FC Product Manual, Rev. C
to be written are already sto red in the cache from a previous read or wr ite 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 segment 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 begin nin g of the operat ion ; 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 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.
Table 16 shows the mode default settings for the drive.
4.5.2Prefetch operation
If the Prefetch feature is enabled, data in conti guous lo gical blocks on the disc i mmedia tely b eyond 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 Rea d comma nds tha t request th ose log ical blocks (this is tr ue even if cache operation is disabled). Though the pr efetch operation uses the buffer as a cache, finding the reques ted data in the
buffer is a prefetch hit, not a cache operation hit.
To enable Prefetch, us e Mode Select page 08h, byte 12, bit 5 (Disable Read Ahea d - DRA bit). DRA bit = 0
enables prefetch.
Since data that is prefetched replaces data already in som e buffer segments, the host can limit the amoun t of
prefetch data to optimize system performanc e. The Max Prefetch field (bytes 8 and 9) limits the amount of
prefetch. The drive does not use the Prefetch Ceiling field (bytes 10 and 11).
During a prefetch operation, the drive cross es a cy linder bou nda ry to fetch more data only if Mode paramete rs
page 08h, byte 2, bit 4 is set to 1 (Discontinuity--DISC bit).
When prefetch (read look-ahe ad) is enabled (enabled by DRA = 0), it operates under the control of ARLA
(Adaptive Read Look-Ahead). If the host uses software interleave, ARLA enables prefetch of contiguous blocks
from the disc when it sense s that a prefetch hit will l ikely occur, even if two consecutive read operations were
not for physically contiguous blocks of data (e.g. “software interleave”). ARLA disables prefetch when it decides
that a prefetch hit will not likely occur. If the host is not using softwa re interleave, and if two sequential read
operations are not for contiguous blocks of data , ARL A dis ables pre fetch, but as long as s equ enti al read oper ations request contiguous blocks of data, ARLA keeps prefetch enabled.
Cheetah 36LP FC Product Manual, Rev. C13
5.0Reliability specifications
The following reliability speci fications assume correc t host and drive operational in terface, including all interface timings, power supply voltages, environmental requirements and drive mounting constraints
Seek error rate:
Read Error Rates
Recovered Data
Unrecovered Data
Miscorrected Data
Interface error rate:
1
Less than 10 errors in 10
Less than 10 errors in 10
Less than 1 sector in 10
Less than 1 sector in 10
Less than 1 error in 10
Less than 1 error in 10
See Section 9.6.4, "Differential PECL input." on page 61
MTBF:1,200,000 hours
Service life:5 years
Preventive maintenance:None required
1.Error rate specified with automatic retries and data correction with ECC enabled and all flaws reallocated.
5.1Error rates
The error rates stated in this manual assume the following:
• The drive is operated in accordanc e with this manual using DC power as d efined in paragraph 6.2, "DC
power requirements."
• The drive has been formatted with the FC-AL Format command.
• Errors caused by media defects or host system failures are excluded from error rate computations.
• Assume random data.
8
seeks
12
bits transferred (OEM default settings)
15
bits transferred
21
bits transferred
12
bits transferred with minimum receive eye.
14
bits transferred with typical receive eye.
5.1.0.1Interface errors
An interface error is defin ed as a failure of the receiver on a por t 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. The total error rate for a loop of devices is the sum of the indi vidual device error
rates.
5.1.1Environmental interference
When evaluating systems operation under conditio ns of electromagnetic int erference (EMI), the performance
of the drive within the system is consid ered ac ceptable if t he dri ve does not gene rate an unrec overable condition.
An unrecoverable error, or condition, is defined as one that:
• is not detected and corrected by the drive itself
• is not detected from the error or fault status provided through the drive or FC-AL interface
• is not recovered by normal drive or system recovery procedures without operator intervention
5.1.2Write errors
Write errors can occur as a result of media defects, environmental interference, or equipment malfunction.
Therefore, write errors are not predictable as a function of the number of bits passed.
If an unrecoverable write error occurs beca use of a n equipm ent mal functi on in the dr ive, the error is classi fied
as a failure affecting MTBF. Unrecoverable write errors are thos e that ca nnot be cor rected wi thin two attem pts
at writing the record with a read verify after each attempt (excluding media defects).
5.1.3Seek errors
A seek error is defined as a failure of the dr i ve to posi tio n th e hea ds to th e ad dr esse d track. After d etec ti ng a n
initial seek error, the drive automatically performs an error recovery process. If the error recovery process fails,
a seek positionin g error (15h) is report ed with a Medium error (3h) or Hard ware error (4h) repo rted in the
14Cheetah 36LP FC Product Manual, Rev. C
Sense Key. Thi s is a n unrecoverable seek error. Unrecoverable seek errors are cl as si fie d a s failures for MTB F
calculations. Refer to the Fibre Channel Interface Manual, part number 77767496, for Request Sense information.
5.2Reliability and service
You can enhan ce the rel iability of Cheetah 36LP FC disc dr ives by ensuring that the dr ive receives adequate
cooling. Section 6 .0 provides re commende d air-flow inform ation, temp erature measur ements, and oth er information, which you can use to enhance the service life of the drive.
5.2.1Mean time between failure (MTBF)
The production disc drive achieves an MTBF of 1,200,000 hours when operated in an environment that
ensures the case temperatures spec ified in Sectio n 6.4.1 are not exceeded. Shor t-ter m excursions up to the
specification limits of th e op erati ng e nvironmen t wi ll not a ffect MTBF p er formanc e. Ope rating th e drive at case
temperatures above these values will adversely affect the drive’s ability to meet specifications. See Section 6.4,
"Environmental limits".
The MTBF target is specified as device power-on hours (POH) for all drives in service per failure.
The following expression defines MTBF:
MTBF per measurement period = Es timated power-on oper ating hours in the period
Number of drive failures in the period
Estimated power-on operating hours means power-on hours per disc drive times the total number of disc drives
in servic e. Each disc dr ive must have accumulated at least ni ne months of op eration. Data is c alculated 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
• Operating at nominal voltages
• System provides adequate cooling to ensure the case temperatures specified in Section 6.4.1 are not
exceeded.
Drive failure means any stoppage or failure to meet defined specifications caused by drive malfunction.
A S.M.A.R.T. p redi ctive failure indicates th at the d r ive is deter iora ting to an imm inent failure and is consi dere d
an MTBF hit.
5.2.2Field failure rate vs time
The expected field failure rate is listed below. Drive utilization will vary. An estimate range of utilization is:
• 720 power-on hours (POH) per month
• 250 on/off cycles per year
• Read/seek/write operation 20% of POH
• System provides adequate cooling to ensure the case temperatures specified in Section 6.4.1 are not
exceeded.
MonthParts per million (PPM)
12,500
21,650
31,200
41,000
5890
6840
7805
Cheetah 36LP FC Product Manual, Rev. C15
Failure rate is calculated as follows:
• No system-induced failures counted
• Based on 1,200,000 MTBF and 720 POH per month
• Month 1’s rate includes a 300 PPM installation failure
5.2.3Preventive maintenance
No routine scheduled preventive maintenance is required.
5.2.4Service lif e
The drive has a usefu l service life of five years. Depot repair or r epl ac eme nt o f ma jor pa rts is permitted dur in g
the lifetime.
5.2.5Service philosophy
Special equipment i s requir ed to repair the dr ive HDA. To achieve the above service l ife, repairs must be performed only at a proper ly equ ipped and s taffed Seagate ser v ice and r epair facili ty. Troubleshooting and repa ir
of PCBs in the field is not recommen ded becaus e of the extensive diagnostic equipm ent required for effective
servicing. There are not spare parts available for this drive. The drive warranty is voided if the HDA is opened.
5.2.6Service tools
No special tools are requi red for site instal lat ion or recomm ended for site maintenance. Refer to Section 5.2.5.
The depot repair philosophy of the drive precludes the necessity for special tools. Field repair of the drive is not
practical because users cannot purchase individual parts for the drive.
5.2.7Hot plugging the drive
Inserting and removing the dr ive on the FC-AL will interrupt l oop operation. Th e interrup tion occurs wh en the
receiver of the next device in the loop must synchronize to a different input signal. FC error detection mechanisms, character sync, running disparity, word sync, and CRC are able to detect any error. Recovery is initiated
based on the type of error.
The disc drive defaults to the FC-AL Moni toring s tate, Pass-through state, when it is powered-on by switching
the power or hot plugged. T he control line to a n optiona l por t bypass circuit (external t o the dr ive), defaults to
the Enable Bypass state. If the bypass circuit is prese nt, the next device in the loop wil l co nti nue to recei ve the
output of the previous device to the newly inserted device. If the bypass circuit is not present, loop operation is
temporarily disrupted until the next device starts receiving the output from the newly inserted device and
regains synchronization to the new input.
The Pass-through state is disabled while the drive performs self test of the FC interface. The control line for an
external port bypass circuit remains in the Enable Bypass state while self test is running. If the bypass circuit is
present, loop operation may continue. If the bypass circuit is not present, loop operation will be halted while the
self test of the FC interface runs.
When the self test completes successfully, the control line to the bypass circuit is disabled and the drive enters
the FC-AL Initializing state. The receiver on the next device in the loop must synchronize to output of the newly
inser ted drive.
If the self-test fails, the control line to the bypass circuit remains in the Enable Bypass state.
Note.
It is the responsibil ity of th e system s inte grator to assu re that no tem perature, ener gy, voltage hazard,
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.
5.2.8S.M.A.R.T.
S.M.A.R.T. is an acro nym for Self-Monito ring A nalysis and Reporting Technology. This technol ogy is intende d
to recognize conditions tha t indicate imminent d rive failure and is designed to provide sufficient warni ng of a
failure to allow you to back up the data before an actual failure occurs.
The drive motor must come to a complete stop prior to changing the plane of operation. This time is
required to insure data integrity.
16Cheetah 36LP FC Product Manual, Rev. C
Note.
The drive’s firmware monitors speci fic attributes for degradation over time but can’t predict instantaneous drive failures.
Each monitored att r ibute has been s elec ted to moni tor a speci fic set of failure condi tions i n the operati ng 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 Informational Exceptions
Control mode page ( 1Ch). Use th e 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 enabled, S.M.A.R.T. collects on-line data as the drive performs
normal read an d write operations. When the PE RF bit is set, the drive is conside red to be in “On-line Mode
Only” and will not perform off-line functions.
You can measure o ff-line attributes and force the dr ive 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 measurement 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. attr ibute data is saved to the disc so th at the events that caused a predictive failure can be r ecreated. The drive measures and saves parameters onc e every two hours subj ect to an idle per iod on the F C-A L
bus. The process of measur i ng off-li ne att r ibute data a nd saving data to the d isc is unin terr uptable. The m aximum 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
50 milliseconds
Fully-enabled delay
DEXCPT = 0, PERF = 0
300 milliseconds
Reporting control
Reporti ng is controll ed by the MRIE b its in the Infor mational E xceptio ns Control mo de page (1C h). Subje ct to
the repor ting me thod, th e firmware will issu e to the host an 01- 5Dxx s ense cod e. The err or code is p reserved
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 rate of degraded errors
increases to an unacceptable level. To determine rate, error events are logged and compared to the number of
total operations for a given attribute. The inte r val defines the numbe r of operat ions over which t o measur e 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. measur es error rates. All erro rs for each monit ored 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 operation. The algorithm that S.M.A.R.T. uses to record rates of error is to
set thresholds for the number of e rrors an d their inte r val. If the numbe r of e rrors exceeds the threshol d before
the interval expires, the error rat e is considered to be unacceptable. If the number of er rors 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. signal s predi ctive failures when the d rive is pe rforming unaccep tably for a period o f time. The f ir mware keeps a running count of the number of times the error rate for each attribute is unacceptable. To accomplish this, a counter is increme nted each time the er ror rate is unacceptable and dec remented (not to exceed
zero) whenever the error rate is acceptable. If the counter continually increm ents such that it reaches the pre-
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