On Mon, 2013-02-04 at 00:57 +0000, Ben Morrow wrote:
I can't give authoratitive answers to either of these, but...
At 6PM -0500 on 3/02/13 you (Joe Beaubien) wrote:
I'm currently trying to setup remote backups of my emails but i'm running into issues (mdbox format, indexes and storage in the same folder hierarchy).
Local backup command: dsync -u "my_user" backup /backups/my_user
(1) Recently, I noticed that the local backup takes up twice the size as the original mail location (8gb vs. 4gb). I purged alot of emails from the original location, so the size shrunk, but the local backup just keeps on getting bigger. I couldn't find any dsync option that would delete extra emails.
- Question: Why isn't the local backup synced properly and remove the extra emails?
Are you running 'doveadm purge' on the backed-up dbox? It looks to me as though dsync doesn't do that. I don't know if there's any (simple) way to do that without a running Dovecot instance attached the dbox directory: it's not entirely clear to me whether doveadm will run locally without contacting a doveadm-server instance running under Dovecot, nor how to point 'doveadm purge' at an arbitrary directory.
Right. doveadm -o mail=mdbox:/backups/my_user purge
It might be easier to dsync to a Maildir instead. This should preserve all the Dovecot-visible metadata, and dsyncing back to the dbox for restore should put it all back.
Better sdbox than maildir.
(2) What is the best why to copy this local backup to a remote location that does NOT have the possibility to run dsync.
Question 1: is rsync safe to use and will this data work for restore?
Question 2: Would it be safe to simply rsync the original mail_location to the remote server?
AFAICT, if Dovecot is stopped on both sides of the transfer it should be safe. If either side has a currently running Dovecot instance (or any other Dovecot tools, like a concurrent dsync) using that dbox, it's likely rsync will copy an inconsistent snapshot of the data, and the result will be corrupted.
It won't be badly corrupted though. At worst Dovecot will rebuild the indexes, which takes a while. And most users probably won't get any corruption at all.