Re: ext3 metadata performace

[Miquel van Smoorenburg]

In article <44635BA8.9060002@xxxxxxxxxx>,
Avi Kivity  <avi@xxxxxxxxxx> 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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