Re: file system and raid performance

From: Mark Kirkwood <markir(at)paradise(dot)net(dot)nz>
To: greg(at)tcscs(dot)com
Cc: 'Mark Wong' <markwkm(at)gmail(dot)com>, david(at)lang(dot)hm, pgsql-performance(at)postgresql(dot)org, 'Gabrielle Roth' <gorthx(at)gmail(dot)com>
Subject: Re: file system and raid performance
Date: 2008-08-07 00:01:57
Message-ID: 489A3B75.6060004@paradise.net.nz
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Gregory S. Youngblood wrote:
>> From: Mark Kirkwood [mailto:markir(at)paradise(dot)net(dot)nz]
>> Mark Wong wrote:
>>
>>> On Mon, Aug 4, 2008 at 10:56 PM, Gregory S. Youngblood
>>>
>> <greg(at)tcscs(dot)com> wrote:
>>
>>>> I recently ran some tests on Ubuntu Hardy Server (Linux) comparing
>>>>
>> JFS, XFS,
>>
>>>> and ZFS+FUSE. It was all 32-bit and on old hardware, plus I only
>>>>
>> used
>>
>>>> bonnie++, so the numbers are really only useful for my hardware.
>>>>
>>>> What parameters were used to create the XFS partition in these
>>>>
>> tests? And,
>>
>>>> what options were used to mount the file system? Was the kernel 32-
>>>>
>> bit or
>>
>>>> 64-bit? Given what I've seen with some of the XFS options (like
>>>>
>> lazy-count),
>>
>>>> I am wondering about the options used in these tests.
>>>>
>>>>
>>> The default (no arguments specified) parameters were used to create
>>> the XFS partitions. Mount options specified are described in the
>>> table. This was a 64-bit OS.
>>>
>>>
>> I think it is a good idea to match the raid stripe size and give some
>> indication of how many disks are in the array. E.g:
>>
>> For a 4 disk system with 256K stripe size I used:
>>
>> $ mkfs.xfs -d su=256k,sw=2 /dev/mdx
>>
>> which performed about 2-3 times quicker than the default (I did try
>> sw=4
>> as well, but didn't notice any difference compared to sw=4).
>>
>
> [Greg says]
> I thought that xfs picked up those details when using md and a soft-raid
> configuration.
>
>
>
>
>
>
You are right, it does (I may be recalling performance from my other
machine that has a 3Ware card - this was a couple of years ago...)
Anyway, I'm thinking for the Hardware raid tests they may need to be
specified.

Cheers

Mark

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