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

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Subject: Re: [Xen-users] RESOLVED: bad I/O performance with HP Smart Array RAID
From: Thomas Aeby <aeby@xxxxxxxxxx>
Date: Tue, 24 Feb 2009 19:47:22 +0100
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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,
Thomas Aeby, Kirchweg 52, 1735 Giffers, Switzerland
Voice : (+41)26 4180040
Internet: aeby@xxxxxxxxxx                       PGP public key available

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