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| Document ID: | I0343-1 |
| Title: | Some Quantum 7200rpm disks may appear slower than Seagate 7200rpm disks when doing single-disk sequential writes (eg: running "mkfile" |
| Copyright Notice: | Copyright © 2005 Sun Microsystems, Inc. All Rights Reserved |
| Last Updated Date: | 1997-08-22 |
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- Sun Proprietary/Confidential: Internal Use Only -
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FIELD INFORMATION NOTICE
(For Authorized Distribution by SunService)FIN #: I0343-1
Synopsis: Some Quantum 7200rpm disks may appear slower than Seagate 7200rpm disks when doing single-disk sequential writes (eg: running "mkfile"Create Date: 21/Aug/97
Keywords:
Some Quantum 7200rpm disks may appear slower than Seagate 7200rpm disks when doing single-disk sequential writes (eg: running "mkfile"
Product Category: STORAGE/DISKS
Product Affected:
SUN4.2G 7200 rpm Quantum disk (VK45J05)
SUN2.1G 7200 rpm Quantum disk (VK22J05)
SPARCstorage Array Model 100 series
SPARCstorage UniPack
SPARCstorage MultiPack
Ultra Enterprise 3000
Ultra 1
Ultra 2
Parts Affected:
370-2809 7200rpm Quantum 4GB 1 inch disk
540-2937 SSA 4GB 7200rpm FRU w/ bracket 540-2764
540-2938 4GB 7200rpm FRU w/ jiffy bracket 540-3124
370-2808 7200rpm Quantum 2GB 1 inch disk
540-2706 SSA 2GB 7200rpm FRU w/ bracket 540-2764
540-2936 2GB 7200rpm FRU w/ jiffy bracket 540-3124
References:
None
Issue Description:
Sun has confirmed the Quantum 7200rpm disk drives meet all established
performance specifications. Also in standard benchmark testing Sun has
determined the performance of Seagate 7200rpm disks and Quantum 7200rpm disks
to be equivalent. However, no two disk designs will exibit identical performance
in all applications. The Quantum 7200rpm disks may experience slower SINGLE
disk sequential write performance than the previously released 2.1GB Seagate
disk. This difference was identified by Sun Engineering when the disks were
initially qualified. At that time, it was considered satisfactory as compared
to the standard 2.1GB 7200rpm disk since overall performance of the Quantum
disks was superior.
All other performance tests, including MULTIPLE drive sequential write tests as
used for a striped volume, show comparable performance for the Seagate and
Quantum drives. SPARCstorage Array disks are normally used with stripes and all
tests completed on multiple 6 disk stripes have been shown to nullify the
performance difference between the Quantum and Seagate disk models. Consequently
sequential write tests on these striped configurations will show comparable
performance between the Quantum and Seagate disk models.
Some customers have expressed concern over slower Quantum performance after
comparing performance of a Quantum drive using a "mkfile" command in a single
disk operation. The following data shows tests performed using the "mkfile"
command.
"mkfile" TEST NOTES:
1). mkfile is not reliably accurate. Repeated identical runs may vary
by several seconds resulting in a +/- 5% accuracy rating. It was
used here because customers are using it to test the drives.
2). %diff, compares the Quantum performance with the Seagate. The larger
the number the better or more equal the disks performance.
3) SSA fast_write d/e, shows numbers with write cache disabled/enabled.
4). Striped volumes were all 2G in size and used ufs and vxva defaults.
5). Tests were done on an Ultra 1 with 64M memory and an SSA11x. Each test
was done with no other i/o going to the SSA. Example of data collection:
# time mkfile 100m /q4/test
0.0u 2.0s 0:10 19% 0+0k 0+0io 0pf+0w
#
6). Quantum 4G = VIKING 4.5 SCA - 8600fw
2G=VIKING VK22J05 - 8600fw
Seagate 4G=ST34371W SUN4.2G 7462fw
2G=ST32550W SUN2.1G 418fw.
------------------------------------------------------------------------------
SSA fast_write d/e d/e d/e
------------------------------------------------------------------------------
time(mins.secs) to- mkfile 100m mkfile 500m mkfile 1000m %diff
------------------------------------------------------------------------------
SIX disk stripe, Six controllers
--------------------------------
Quantum 4G .08/.06 .42/.31 1.24/1.02 87/98%
Seagate 4G .07/.06 .37/.30 1.13/1.01
Quantum 2G .08/.06 .42/.31 1.24/1.02 96/98%
Seagate 2G .08/.06 .40/.30 1.21/1.01
5 Seagate 1 Quantum 4G .07/.06 .37/.30 1.17/1.01
4 Seagate 2 Quantum 4G .08/.06 .39/.30 1.19/1.01
3 Seagate 3 Quantum 4G .08/.06 .40/.30 1.20/1.01
2 Seagate 4 Quantum 4G .07/.06 .39/.30 1.18/1.01
1 Seagate 5 Quantum 4G .08/.06 .41/.31 1.23/1.02
THREE disk stripe, Three controllers
------------------------------------
Quantum 4G .10/.07 .53/.39 1.45/1.20 70/80%
Seagate 4G .07/.06 .37/.30 1.13/1.05
Quantum 2G .10/.06 .53/.39 1.47/1.20 68/81%
Seagate 2G .07/.06 .36/.32 1.13/1.03
2 Seagate 1 Quantum 4G .07/.06 .39/.30 1.17/1.01
1 Seagate 2 Quantum 4G .10/.07 .51/.39 1.42/1.19
SINGLE Disk
-----------
Quantum 4G .25/.21 2.15/1.58 43/47%
Seagate 4G .11/.10 .58/.55
Quantum 2G .25/.20 2.08/1.54 64/70%
Seagate 2G .16/14 1.22/1.20
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"mkfile" TEST CONCLUSIONS:
1). Single disk performance shows the 4G Quantum performing at about 45%
(55% less) of the Seagate. Quantum 2G disks about 65% (45% less) of
the 2G Seagate Cuda2.
2). Three disk stripe improves to about 80% (20% less).
3). Six disk stripe improves to about 90% (10% less), but if you enable
the SSA fast_write write cache the performance becomes equal.
4). Disks as shipped in the SSA product are normally striped and fast_write
enabled. All tests using this standard configuration, including mixed
disks, show equivalent performance.
Although performance results in this case are acknowledged to be lower,
overall performance, and performance in normal applications has been
measured to be equivalent or in some cases BETTER with the Quantum drive.
Other single 4G disk tests using standard Unix commands:
---------------------------------------------------------
time newfs /dev/rdsk/c1t1d4s2:
Seagate = 4.56
Quantum = 4.53 101%
time cp /mnt/500m /s4:
Seagate = 1.20
Quantum = 2.07 63%
time cp -r /usr/share/man /s4/tmp:
Seagate = 4.59
Quantum = 4:56 101%
time cp -r /s4/tmp /tmp:
Seagate = 1.21
Quantum = 1.16 107%
time tar -cf - usr/share/man|(cd /s4; tar -xf -):
Seagate = 4.31
Quantum = 4.28 101%
time tar -xf /tmp/tarfile:
Seagate = 4.20
Quantum = 4.22 99%
time tar -cf /dev/null /s4:
Seagate = .47
Quantum = .47 100%
time ufsdump 0f /dev/null /dev/rdsk/c1t1d2s2:
Seagate = .52
Quantum = .46 113%
time ufsrestore 0f /tmp/dumpfile:
Seagate = 4.22
Quantum = 4.22 100%
----------------------------------------------------------
As shown above the Quantum disks show equal or superior performance for all
tested Unix commands except a large sequential file cp (sequential write).Corrective Action:
None required, this data is provided for information only. It is recommended
that SPARCstorage Array users configure data in multiple disk stripes and
enable fast writes when possible for best performance.
Comments:
Technology improvements will continue to produce differences in drives. New
generation products are not identical, but may be considered equivalent in
overall performance. Sun does strive to keep minimum performance differences
in a product when choosing multiple suppliers. Quantum drives have met the
required specifications for overall performance.
This information applies to Quantum disks with revision 8600 firmware only.