On 24 February 2018 at 15:47 Neil Jerram neil@ossau.homelinux.net wrote:
Aki Tuomi aki.tuomi@dovecot.fi writes:
On 24 February 2018 at 12:45 Neil Jerram < neil@ossau.homelinux.net> wrote:
Please could you help me to understand and fix why my dovecot IMAP performance is so bad? I've read through a lot of the performance-related material on the website, but I don't think that any of it could account for slowness at the level that I am seeing.
The simplest scenario is moving a message from my Inbox to another IMAP folder. Using Gnus as the client, the whole UI freezes for about 2 minutes (which I assume is until the move is complete), and journalctl on the dovecot server says:
Feb 24 10:24:24 arudy dovecot[1712]: imap(neil): Warning: Transaction log file /home/neil/dovecot-mail/.imap/INBOX/dovecot.index.log was locked for 98 seconds (Mailbox was synchronized)
or the same message with (rotating while syncing).
There must be something badly wrong in my setup, or perhaps in the spec of the server that dovecot is running on. What should I look at to start understanding this better?
Many thanks - Neil
Can you tell a bit more about your environment? Sounds like io issue
Thanks for your reply. I'm not sure exactly what you have in mind, but here are some starting points:
arudy:~# uname -a Linux arudy 4.13.0-1-686-pae #1 SMP Debian 4.13.4-2 (2017-10-15) i686 GNU/Linux
arudy:~# dovecot -n # 2.2.32 (dfbe293d4): /etc/dovecot/dovecot.conf # Pigeonhole version 0.4.20 (7cd71ba) # OS: Linux 4.13.0-1-686-pae i686 Debian buster/sid auth_mechanisms = plain login auth_username_format = %Ln auth_verbose = yes login_trusted_networks = 192.168.11.8 mail_access_groups = mail mail_fsync = never mail_location = mbox:~/dovecot-mail:INBOX=/var/mail/%u
You are using mbox format. This is ... bit slow. =)
When you move mails between mbox files, it has to rewrite the entire mbox file every time. You should probably start using maildir or sdbox instead.
Aki