[Linux-cluster] GFS tuning advice sought

[James Fidell]

I have a 3-node cluster built on CentOS 5.1, fully updated, providing
Maildir mail spool filesystems to dovecot-based IMAP servers.  As it
stands GFS is in its default configuration -- no tuning has been done
so far.

Mostly, it's working fine.  Unfortunately we do have a few people with
tens of thousands of emails in single mailboxes who are seeing fairly
significant performance problems when fetching their email and in this
instance "make your mailbox smaller" isn't an acceptable solution :(

Is there any GFS tuning I can do which might help speed up access to
these mailboxes?

Thanks,
James