Replication and Deleted Files

[Ian Batten]

Hi, long-time Cyrus user (25 years, I think), but stumped on this one…

I have an ancient Cyrus 2.5.11 on Solaris 11 installation I am trying to migrate off.  The strategy is to run rolling replication onto the new server (3.0.8-6+deb10u4 on Debian 10.4), and then point the DNS record at the new server.  With Covid, this has become more protracted than I would like, as I don’t want to accidentally mess up users who are isolating, so the replication has been running for some weeks.

The replication structure is old-server -> new-server -> (backup1, backup2) where backup1 and backup2 are configured as separate channels on new-server.  This has been running seemingly correctly for about three months now.

Today I decided to check all was well by using rsync -an to confirm that the replicas have everything that is on the master.  They do, in that using 

rsync -anvO --size-only  --exclude='cyrus.*' root at mail:/var/imap/partition1/user/ /var/imap/partition1/user 

where “mail” is the old server shows that there are no messages missing (—size-only because there’s some time slew in a few places, usually only of a few seconds, but up to a day in others).

However, reversing it:

rsync -anvO --size-only  --exclude='cyrus.*' /var/imap/partition1/user/ root at mail:/var/imap/partition1/user

Shows that there are a _lot_ of files on the replicas which are not on the master, some of them relating to recent deletions, but some of them seemingly quite old.  I am using:

delete_mode: delayed
expunge_mode: delayed

everywhere, running cyr_expire on the master but not on the replicas.  I have enough bandwidth that sync_reset and re-sync is realistic, but I’d rather not have to do that immediately prior to a cut-over.   These old files are a worry because if I ever had to reconstruct one of the mailboxes, presumably the deleted (I think) messages would all reappear.  Does anyone have any suggestions?

Thanks

ian
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