[Dovecot] Dovecot "sleep" for short snapshots

Peer Heinlein p.heinlein at heinlein-support.de
Sat Dec 15 09:52:39 EET 2012



Making consistent backups from Dovecot with mdbox requires a snapshoted
filesystem with (at least) a short Downtime for Dovecot.

I'd like to avoid killing several thenthousand IMAP-sessions for 60
seconds. Users don't like that... And the admin dislakes that too...

What about a "short sleep" mechanism for Dovecot, where all writes are
finished and new writes are easily delayed?

I'd like to following process:

*) "doveadm sleep" puts Dovecot in sleep-Mode:
  -- All existing writes are finished (before "doveadm sleep" is allowed
 to exit)
  -- All new writes are simply delayed
  -- All readonly-operations could work normally, so users can fetch and
read mails

*) The the admin can create a LVM-/SAN-snapshot of the filesystems

*) "doveadm unsleep" will finish the magic

Overall the whole process will take just some seconds.

Users will recognize a simple write-delay, but they can work normally
and the aren't unconnected at all. If the snapshot is really fast the
users won't recognize the whole situation at all.


Peer

-- 
Heinlein Support GmbH
Schwedter Str. 8/9b, 10119 Berlin

http://www.heinlein-support.de

Tel: 030 / 405051-42
Fax: 030 / 405051-19

Zwangsangaben lt. §35a GmbHG:
HRB 93818 B / Amtsgericht Berlin-Charlottenburg,
Geschäftsführer: Peer Heinlein -- Sitz: Berlin



More information about the dovecot mailing list