Re: [Xen-users] RESOLVED: bad I/O performance with HP Smart Array RAID

[Thomas Aeby <aeby@xxxxxxxxxx>]

Ok, sorry for having thought this might be a XEN issue.

Multiple Smart Array controllers are known for their really bad disk 
write performance. The controller on the machine in question is an 
E200i. I have seen many complaints from users out there that around 
10-12 MB/s write throughput is about what one can expect from this 
controller and even an inofficial citation from HP support classifying 
this problem as a "feature".
So far, there seems to be no real solution - a few users have 
successfully been able to improve performance by enabling the drive 
write caches (which of course is dangerous). My controller does not seem 
to support this option at all.
The only real solution seems to get rid of the controller and either use 
the disks with a normal SATA-controller with software RAID (where you 
can expect 50-100MB/s - a real performance boost) or buy a less trashy 
RAID controller.
I do not know yet what we are going to do. So far I know that we must 
avoid many HP so-called-servers with I/O-performance of a desktop PC of 
the mid-90s.
Best regards,
Tom
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Thomas Aeby, Kirchweg 52, 1735 Giffers, Switzerland
Voice : (+41)26 4180040
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