From: Kanoalani Withington <kanoa@cfht.hawaii.edu>
To: Luca Berra <bluca@comedia.it>
Cc: Gordon Henderson <gordon@drogon.net>, linux-raid@vger.kernel.org
Subject: Re: raid5: switching cache buffer size
Date: Fri, 13 Dec 2002 09:17:15 -1000 [thread overview]
Message-ID: <3DFA323B.3000103@cfht.hawaii.edu> (raw)
In-Reply-To: 3DFA2E2A.20601@comedia.it
You might also be using a journaled filesystem with the journal on the
same volume as the data. XFS does this by default for example, writes to
the journal are not the same block size as writes to the data volume so
the RAID layer reports tons of messages like the ones you describe. The
proper solution (according the XFS maintainers) is to create a small
disk mirror for the journal separate from the data volume.
-Kanoa
Luca Berra wrote:
> Gordon Henderson wrote:
>
>> Anyone know what this means?
>>
>> My big server is currently fscking a lvm partition which sits on-top
>> of a
>> raid5 device and the console is scrolling these messages as fast as
>> it can.
>> It says it's switching from 0 to 512, from 512 to 0 and 0 to 1024 ( or
>> maybe 512 to 1024, its hard to tell).
>>
>> What's happening and how do I stop it?
>
>
> hi,
> you probably have filesystems of different block in the volume group,
> raid cache cannot cope with requests of varying block size so it has
> to flush the cache each time, this only hurts performance and is not
> problem for data safety.
>
> fix:
> 1) make sure everything on your raid5 is the same block size, if you
> have swap you are locked to using 4k blocks, if you are using
> snapshots 1k blocks, if you use both jump.
> 2) comment the printk in the raid5 source
>
> L.
>
>
> -
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>
>
next prev parent reply other threads:[~2002-12-13 19:17 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-12-10 9:42 FSCK and it crashes Gordon Henderson
2002-12-10 10:22 ` Wim Vinckier
2002-12-10 18:58 ` Steven Dake
2002-12-10 19:04 ` Gordon Henderson
2002-12-13 15:38 ` raid5: switching cache buffer size Gordon Henderson
2002-12-13 18:59 ` Luca Berra
2002-12-13 19:17 ` Kanoalani Withington [this message]
2002-12-13 22:29 ` Gordon Henderson
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