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Slow Speed Tests - Perc6i + 8 x 1.5TB RAID 10

Posted on 2012-04-03
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Last Modified: 2012-06-27
Hey guys

Got a a Dual Quad Core 32GB Server
Perc6i with BBU
8 x 1.5TB WD RE4 RAID 10
Filesystem: EXT4
Strip: 64K

Its running slow or these commands are wrong, any help would be appreciated

root@svr1:~# hdparm -Tt /dev/sdb1

/dev/sdb1:
 Timing cached reads:   14932 MB in  2.00 seconds = 7473.84 MB/sec
 Timing buffered disk reads: 682 MB in  3.00 seconds = 227.30 MB/sec
root@svr1:~# hdparm -tT /dev/sdb1


root@svr1:~# dd if=/dev/sdb1 of=test bs=64k count=16k conv=fdatasync
16384+0 records in
16384+0 records out
1073741824 bytes (1.1 GB) copied, 14.9253 s, 71.9 MB/s
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Question by:nbrooky
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3 Comments
 
LVL 55

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andyalder earned 250 total points
ID: 37805027
Looks reasonable to me for 7.2K disks.

227MB/s 64K blocksize = 3632 IOPS (far better than expected but it's sequential data so that's believable)

71MB/s 64K blocksize 1136 IOPS, again better than expected but again sequential data. Much worse than the previous but there again of=test is probably on the same disks so you're reading from the same thing you're writing to which makes for a lot more head movement.

What figures were you expecting?
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LVL 47

Assisted Solution

by:David
David earned 250 total points
ID: 37805449
YOur performance will "double" if you use the bitbucket as source of the data instead of existing drives, i.e, use if=/dev/zero  
As Andyalder posted, the numbers you got are quite reasonable.   SATA disks and performance are somewhat mutually exclusive.
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Author Closing Comment

by:nbrooky
ID: 37808879
Thanks guys totally forgot what I was testing here did think about block size of the writes :)
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