On 18/10/2022 12:17, Michael wrote:
[...] so, raid is mandatory, which is already the case, but what about backup? how can i achieve a backup/snapshot of both, the mdbox (nfs share) and the index files (local raid) and assure they are consistent?
You can use doveadm to backup the mailboxes, which should work correctly even in a live system.
My backup "strategy" (hopefully it deserves that name) is to weekly run something like:
for MAILBOX in $USERS; do doveadm expunge -u "$MAILBOX" mailbox Trash savedbefore 7d doveadm expunge -u "$MAILBOX" mailbox Spam savedbefore 30d doveadm purge -u "$MAILBOX"
LOCATION2="mdbox:/srv/snap_mail/$MAILBOX/mdbox"
doveadm -v backup -u "$MAILBOX" -P "$LOCATION2"done
which makes a replica of the mailbox (including dovecot.list.index, but e.g. dovecot-uidvalidity is not there, I don't know if this is bad or not).
Once you have this "snapshot" of the mailbox(es), you can rsync them to wherever you like (so you avoid rsync'ing a changing system).
I've never had to restore from backup (rsync back, and either doveadm backup back in the other direction), but I'd tend to assume this should work fine.
BTW I use mdbox_rotate_interval = 0 and mdbox_rotate_size = 64M, so the mdbox'es have a relatively big size (but not too big), which is nice for rsync.
Cheers, Bernardo