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DL140 G3 bad SAS RAID performance in Linux

 

DL140 G3 bad SAS RAID performance in Linux

Hi,


I installed CentOS 4.5 i386 (RHEL4 Update 5 clone) on DL140 G3 with SmartArray E200 RAID controller and 2 SAS 15k rpm HDDs (RAID1, mirror). The problem is that hdparm disk benchmark test shows really low results:

# hdparm -t /dev/cciss/c0d0

/dev/cciss/c0d0:
Timing buffered disk reads: 84 MB in 3.02 seconds = 27.82 MB/sec
HDIO_DRIVE_CMD(null) (wait for flush complete) failed: Inappropriate ioctl for device

Also tried a simple test with dd (copying 8 GB of raw data from /dev/cciss/c0d0 to /dev/null with block size 4k) - it transfered 8 GB in ~293 s - ~27.9 MB/s.

I expected waaaay better performance, because even software SATA RAID1 (mirror) can easily do 50-60 MB/s.

And yes, my system was completely idle during tests (load averages 0.00 before the tests, with all the services off).

So where's the problem?

Thanks in advance.
1 REPLY 1

Re: DL140 G3 bad SAS RAID performance in Linux

It seems that the problem disappears in CentOS 5.0 (RHEL5) - hdparm results are much better:

# hdparm -t /dev/cciss/c0d0

/dev/cciss/c0d0:
Timing buffered disk reads: 392 MB in 3.02 seconds = 129.78 MB/sec
HDIO_DRIVE_CMD(null) (wait for flush complete) failed: Inappropriate ioctl for device