[Dovecot] Dovecot performance issues with many writes

[Timo Sirainen]

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?