[Dovecot] mail open slowly

[Stan Hoeppner]

On 10/27/2012 6:58 AM, Bernics Gábor | Penta Unió Zrt. wrote:

> I use dovecot LDA (+sieve) with maildir. 
> 
> conf:
> 
> http://pastebin.com/9fhYD58g

Next time simply paste "dovecot -n" output into your email.

Assuming Dovecot is the only program accessing the maildirs, try:

maildir_very_dirty_syncs=yes

That may help some.

It may not have been a factor in this case, but note that when anyone is
doing a full text search on a large mailbox on this hardware with
maildir you will see latency, and it is unavoidable.  Neither a single
7.2K SATA spindle nor md/RAID1 pair of them, has enough seek capacity to
service all the sector requests in a timely fashion.

Also, I noticed you disabled fsync.  This is a very very bad idea for a
mail server.  If you lose power, or suffer a kernel/hardware/etc crash,
you lose the Linux buffer cache contents.  Thus, you may lose emails
that haven't been flushed to disk, and possibly get index file
corruption if mmap'd pages haven't been flushed.

Running with fsync disabled is like having sex with a Bangkok prostitute
without a condom while juggling chainsaws while driving drunk at 250kph
at night without headlights.

fsync does hurt write performance to a degree, especially with maildir
storage, but will likely be invisible on a small server with few
users/light load.  And it will prevent potentially severe problems with
file corruption and/or lost emails.

-- 
Stan