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

To: Thomas Aeby <aeby@xxxxxxxxxx>
Subject: Re: [Xen-users] RESOLVED: bad I/O performance with HP Smart Array RAID
From: "Fajar A. Nugraha" <fajar@xxxxxxxxx>
Date: Wed, 25 Feb 2009 07:50:26 +0700
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On Wed, Feb 25, 2009 at 1:47 AM, Thomas Aeby <aeby@xxxxxxxxxx> wrote:
> Ok, sorry for having thought this might be a XEN issue.

Glad you solved it!

> 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

I considered that option once, but the thing is some (if not most) HP
servers NEEDS RAID controller and doesn't even offer plain SATA
controller. Yaiks.

> 50-100MB/s - a real performance boost) or buy a less trashy RAID controller.

I usually stick to the one with 512MB battery-backed cache.



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