Ext3 Performance Tuning - the journal

[Brice Figureau]

Hi,

On Tue, 2007-12-11 at 13:29 +0100, Sven Rudolph wrote:
> I have some performance problems in a file server system. It is used
> as Samba and NFS file server. I have some ideas what might cause the
> problems, and I want to try step by step. First I have to learn more
> about these areas.
> 
> First I have some questions about tuning/sizing the ext3 journal.
> 
> The most extensive list I found on ext3 performance tuning is
> <http://marc.info/?l=ext3-users&m=117943306605949&w=2> .
> 
> 
> I learned that the ext3 journal is flushed when either the journal is
> full or the commit interval is over (set by the mount option
> "commit=<number of seconds>"). So started trying these settings.

Are your filesystem mounted noatime ?

It does a huge difference, especially if your workload is mainly read
over write.
Without noatime, each access to a file generates a write to change the
metadata which will fill your journal.

If you are not using noatime, it is worth trying it.
See it for a thorough discussion of the topic:
http://thread.gmane.org/gmane.linux.kernel/565148

Hope that helps,
-- 
Brice Figureau
Days of Wonder http://www.daysofwonder.com/