[Dovecot] mail location filesystem noatime, nodiratime?

[Stan Hoeppner]

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