On 12/15/2012 1:52 AM, Peer Heinlein wrote:
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...
Are you sure it is necessary? I'm not very familiar with mdbox, but given the rundown on the wiki, it looks as though it should be very resilient to snapshots even mid-write. With fs-freeze and the nature of bulk writes, I suspect it should be fine. At worst, it might need to regain sanity off the backup indexes. Since file rewrites are done during the purge script, I'd definitely not do snapshots during the purge.
The last I checked, the fs-freeze api isn't complete. It would make more sense for dovecot to work with that structure once it is completed (allowing fs-freeze to inform dovecot that the fs will be freezing/unfreezing).
Jack