Without FTS, dovecot needs to open *each* and *every* email when doing
text searches, which is understandably rather slow process.
Aki
On 27.2.2019 10.43, Marc Roos wrote:
>
>
> I am not sure if this any help. From what I understand of maildir it has
> lots of separate files, thus uid/gid lookups. Try running something like
> nscd, that will cache these lookups?
>
>
>
>
> -Original Message-
> From: Aki Tuomi via dovecot [mailto:dovecot@dovecot.org]
> Sent: 27 February 2019 06:24
> To: Ben Burke; Dovecot Mailing List
> Subject: Re: performance issue with UID SEARCH
>
>
> On 27 February 2019 03:27 Ben Burke via dovecot <
> dovecot@dovecot.org> wrote:
>
>
> Hi,
>
> I'm running dovecot 2.2.x and I'm having an issue where I see many
> dovecot processes use all the available IO on a server. According
> to
> iotop the worst offenders seem to be in this state (NOTE: I swapped
> in
> phony username & IP info):
>
> dovecot/imap [someusername 123.456.789.012 UID SEARCH]
>
> The server in question is running with Maildirs on top of an XFS
> filesystem. Is there anything I can do to optimize "UID SEARCH" or
> find
> out why it's being a problem? I've read
> https://wiki2.dovecot.org/PerformanceTuning and the linked pages.
>
> By "being a problem" I mean iostat -xmt 1 /dev/diskdevice shows
> 100%
> utilization for long periods and in some cases io service times are
>
> taking many seconds... which causes thunderbird to timeout when
> doing
> things like appending messages to user "Sent" mailboxes.
>
> Any ideas?
>
> Thanks,
> Ben Burke
>
>
> Are you using FTS? If not, you should. See
> https://wiki.dovecot.org/Plugins/FTS
> ---
> Aki Tuomi
>
>
