I've noticed some slowness on one of my toasters. Looking at stats collected by sar, I see 10-20% iowait during peak hours.
Running iotop I can see processes taking 100 % IO during disk write: pdflush kjournald dovecot/imap The disk setup is not optimal for mail server use: I have 3ware RAID controller running RAID-5 with SATA disks. I have 3072M memory, no swap used, 1200M cached. I would prefer not to change any hardware at this point, so I am looking for other options such as tweaking Dovecot. Reading http://wiki.dovecot.org/MailLocation/LocalDisk I see that one option would be to disable fsyncing. But when looking at /etc/dovecot/conf.d/10-mail.conf all I see is: #mail_fsync = optimized So no fsync_disable option there? Has anyone tried to modify this parameter? Any other advice? Perhaps moving webmails to another server would be one option, I do see sometimes httpd also in the iotop listing taking cpu... Regards, Peter
