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Old 11-03-2009, 11:45 PM   #1
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I/O problem -- dd if=/dev/zero of=bf bs=8k count=500000

Hi all together,

i think that i have some I/O Problems with my HP Proliant Servers (not all).
So i did the following Test on some of my servers (different models, different OS):

bash> sync; time dd if=/dev/zero of=bf bs=8k count=500000; sync

This writes a 4GB File to the disk and measures the writespeed and the time.
and for Read i used hdparm:

bash> hdparm -t /dev/cciss/DEV (wasn't installed on the all servers so i left some results as XX)

So i have the following servers/results(sorted by write speed):

W: 92 MB/s - R: 97 MB/s - DL380 G5 - SuSE 10.3
W: 65 MB/s - R: 59 MB/s - DL360 G4 - SLES10
W: 45 MB/s - R: XX MB/s - DL385 G1 - Solaris10
W: 40 MB/s - R: XX MB/s - DL320 G3 - SLES9
W: 35 MB/s - R: 49 MB/s - DL380 G3 - RedHat ES 3
W: 32 MB/s - R: 56 MB/s - DL320 G2 - SuSE 10.1 (Linux Softraid)
W: 32 MB/s - R: 56 MB/s - DL380 G3 - SLES10
W: 28 MB/s - R: XX MB/s - DL380 G3 - SuSE 10.3
W: 22 MB/s - R: XX MB/s - DL380 G3 - SLES8

The strange thing is on my desktop workstation (also hp) i get a much better performance:

W: 50 MB/s - R: 72 MB/s - dc5700 - Ubuntu 8.10

Can anybody explain that? Or do i just do the wrong tests? It's really strange that a softraid or my desktop pc are faster dann the SA controllers.
Old 11-04-2009, 05:28 PM   #2
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