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
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