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Re: Experience with HP Smart Array P400 and SATA drives?

From: "Scott Marlowe" <scott(dot)marlowe(at)gmail(dot)com>
To: "Mario Weilguni" <mweilguni(at)sime(dot)com>
Cc: "Alan Hodgson" <ahodgson(at)simkin(dot)ca>, pgsql-performance(at)postgresql(dot)org
Subject: Re: Experience with HP Smart Array P400 and SATA drives?
Date: 2008-12-09 15:30:38
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-performance
On Tue, Dec 9, 2008 at 5:17 AM, Mario Weilguni <mweilguni(at)sime(dot)com> wrote:
> Alan Hodgson schrieb:
>>>>>> Mario Weilguni <mweilguni(at)sime(dot)com> wrote:
>>>> strange values. An individual drive is capable of delivering 91
>>>> MB/sec
>>>>      sequential read performance, and we get values ~102MB/sec out of a
>>>> 8-drive RAID5, seems to be ridiculous slow.
>> What command are you using to test the reads?
>> Some recommendations to try:
>> 1) /sbin/blockdev --setra 2048 device (where device is the partition or
>> LVM volume)
>> 2) Use XFS, and make sure your stripe settings match the RAID.
>> Having said that, 102MB/sec sounds really low for any modern controller
>> with 8 drives, regardless of tuning or filesystem choice.
> First, thanks alot for this and all the other answers.
> I measured the raw device performance:
> dd if=/dev/cciss/c0d0 bs=64k count=100000 of=/dev/null
> I get poor performance when all 8 drives are configured as one, large
> RAID-5, and slightly poorer performance when configured as JBOD. In
> production, we use XFS as FS, but I doubt this has anything to do with FS
> tuning.

Yeah, having just trawled the pgsql-performance archives, there are
plenty of instances of people having terrible performance from HP
smart array controllers before the P800.  Is it possible for you to
trade up to a better RAID controller?  Whichever salesman sold you the
P400 should take one for the team and make this right for you.

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Subject: Re: Experience with HP Smart Array P400 and SATA drives?
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Subject: Re: Need help with 8.4 Performance Testing

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