[Dovecot] Dovecot performance issues with many writes

[Andy Robbins]

Well, the iostat command was run from the NFS server and dovecot was run
from the mail server where it is mounted, hence the discrepancy there.


On Thu, Nov 17, 2011 at 4:34 PM, Timo Sirainen <tss at iki.fi> wrote:

> On 18.11.2011, at 0.20, Andy Robbins wrote:
>
> > # iostat -d 5 -x
> > Device:         rrqm/s   wrqm/s     r/s     w/s   rsec/s   wsec/s
> avgrq-sz
> > avgqu-sz   await  svctm  %util
> > dm-4              0.00     0.00  485.80  865.80  3886.40  6926.40
> > 8.00    28.69   19.63   0.70  94.00
> > drbd0             0.00     0.00  485.80  865.80  3886.40  6926.40
> > 8.00   111.42   94.44   0.74  99.60
>
> These devices don't look like NFS, but you have:
>
> > mmap_disable: yes
> > mail_nfs_storage: yes
> > mail_nfs_index: yes
>
> So what filesystem is that? Are they storing only mails, or other stuff
> too (like logs)? The mail_nfs_*=yes are probably not needed and are slowing
> things up at least somewhat..
>
> > lda:
> >  fsync_disable: no
>
> This is explicitly set for LDA, but it's the default already elsewhere.
> Maybe you wanted to try fsync_disable=yes elsewhere except in LDA?
>
>
>