From: | Mario Weilguni <mweilguni(at)sime(dot)com> |
---|---|
To: | Alan Hodgson <ahodgson(at)simkin(dot)ca> |
Cc: | pgsql-performance(at)postgresql(dot)org |
Subject: | Re: Experience with HP Smart Array P400 and SATA drives? |
Date: | 2008-12-09 12:17:37 |
Message-ID: | 493E61E1.1020303@sime.com |
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Thread: | |
Lists: | pgsql-performance |
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.
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