From: "Miquel van Smoorenburg" <miquels@cistron.nl>
Subject: Re: ext3 metadata performace
Date: Thu, 11 May 2006 18:46:07 +0000 (UTC)
Organization: Cistron
Message-ID: <e400pf$ens$1@news.cistron.nl>
References: <4463461C.3070201@conterra.de> <44635BA8.9060002@argo.co.il>
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Originator: mikevs@n2o.xs4all.nl (Miquel van Smoorenburg)
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In article <44635BA8.9060002@argo.co.il>,
Avi Kivity  <avi@argo.co.il> wrote:
>Dieter Stuken wrote:
>> after I switched from from ext2 to ext3 i observed some severe 
>> performance degradation. Most discussion about this topic deals
>> with tuning of data-io performance. My problem however is related to 
>> metadata updates. When cloning (cp -al) or deleting directory trees I 
>> find, that about 7200 files are created/deleted per minute. Seems
>> this is related to some ex3 strategy, to wait for each metadata to be
>> written to disk. Interestingly this occurs with my new hw-raid
>> controller (3ware 9500S), which even has an battery buffered disk cache.
>> Thus there is no need for synchronous IO anyway. If I disable the
>> disk cache on my plain SATA disk using ext3, I also get this behavior.
>>
>Try increasing the journal size (mkfs -t ext3 -J size=20000) and see if 
>that improves things.

Also, with 3ware, look in /sys/block/sd* and set queue_depth to
254/(nr_arrays), and nr_requests to at least 2*queue_depth. Also
try another I/O scheduler (deadline instead of as).

Mike.

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