On 19.5.2010, at 16.39, Gregory Finch wrote:

My install uses XFS with noatime on all mount points and works perfectly... I haven't tried it with nodiratime yet apparently.. I

noatime also implicitly enables nodiratime. No need to specify both.

And yeah, Dovecot doesn't need automatic atime updates. It does use atimes to scan once in a while for some temp files that have been left lying around, but it explicitly changes the atime afterwards.

Heiko Schlichting put forth on 5/19/2010 9:44 AM:

...

Will Dovecot be negatively impacted if I change my XFS mount options to noatime,nodiratime?

How are the mails stored on your XFS filesystem? For Maildir, there is no problem using these mount options. I'm using

noatime,nodiratime,nobarrier,logbufs=8

I'm using mbox files in user home dirs. /home is 100GB XFS created with mkfs.xfs defaults and currently mounted with defaults. I use LDA and most users have sieve scripts. FTS squat gets a fair amount of use. Users hit dovecot via Tbird/etc and via local Roundcube webmail. Server also hosts some static web content. Fairly low volume low load server for the most part, no hardware RAID, two 500GB 7.2K SATA disks mirrored. Home dirs are also exported via Samba. Things can bog down a bit now and then due to the combination of services so I'm trying to optimize settings a bit for a little snappier performance.

for mounting XFS filesystems on all my dovecot servers for years without any problems. Mailstorage is Maildir (written by exim not dovecot lda but this should not matter).

nobarrier is enabled because I use RAID systems with battery backed write cache.

I've wandered about barrier for a while now. I don't grasp its effect on non HW RAID disks. I don't currently specify barrier at mount, but hdparm says my disks' write caches are enabled. Are they? Should I specify barrier in fstab? Again, no HW RAID, but the server is backed by a beefy net enabled APC UPS and a low battery auto shutdown script.

logbufs=8 does increase performace for deleting mails (e.g. for expiring the Spam folder) if XFS log is internal (the default). If you have configured a separate, external partion for XFS log, this might not be necessary.

My disk logs are internal. I've toyed with the idea of increasing logbufs or logbsize since the defaults are pretty small. I use a 4K block size, so I only have 2 logbufs of 32K each. Is it better to increase logbufs or logbsize?

Heiko

Thanks for the tips Heiko.

-- Stan