[Linux-cluster] GFS performance of imap service (Maildir)

[Achievement Chan]

Dear All,
I've setup a courier-imap server which store the email data in Maildir format.
The mailbox are saved under a LUN in ISCSI SAN.

For handling a mailbox with 10000 email, it takes 6-8 seconds for
waiting response from first "SELECT" command.
The response time is also unstable too, sometimes it takes 10-20
seconds for the same mailbox.

Based some online material, i've tried to tune the gfs. But there are
seems no improvement.
e.g.
gfs_tool setflag inherit_jdata /home/domains
gfs_tool  settune /home/domains recoverd_secs 60
gfs_tool settune /home/domains glock_purge 50
gfs_tool settune /home/domains demote_secs 100
gfs_tool settune /home/domains scand_secs 3
gfs_tool settune /home/domains max_readahead 262144
gfs_tool settune /home/domains statfs_fast 1


I've tested the mailbox under ext3 and gfs2, both under the LUN in the
same SAN.
The response time can be within 1 second.

Has anyone tried to provide imap service in GFS?

or I need to go for GFS2? Is GFS2 still unstable for production system?


Regards,
Achievement Chan