migration with doveadm backup to new cluster running dovecot 2.2.36 and replicator

[Thomas Winterstein]

No one?

If there are limitations in regards to how dsync in migration and 
replication can operate together these should be stated clearly in the 
documentation.

On 23.12.2020 20:33, Thomas Winterstein wrote:
> Hello everyone,
> 
> 
> we are working on migrating from dovecot 2.0.9 (maildir) to 2.2.36 
> (mdbox). The new cluster has two backend mail servers which replicate 
> through doveadm replicator. To move the data initially we use doveadm 
> backup (imapc).
> 
> arb
> Our migration command
>   doveadm -o mail_fsync=never backup -R -u $user imapc:
> 
> 
> To test the replication of new and purge of old mails with live data 
> changes we ran imapc on a daily basis but encountered the problem that 
> some mailboxes multiplied in size. We then made sure that imapc and 
> replication don't run at the same time but after the first incremental 
> imapc process, we still had the same problems.
> 
> 
> The doveadm-backup man-page states that it's possible to run it multiple 
> times during migration. But is it also possible to have the replicator 
> running in between? From our understanding the doveadm backup should 
> just work as an imap connection between the servers, synchronizing all 
> changes made on the source to the destination. Or does the conversion 
> from maildir to mdbox format in our case produce the problems?
> 
> 
> If you're not supposed to run the replicator before having fully 
> migrated, how can we shorten the downtime? rsync? And how can we be sure 
> that similar problems don't occur after the migration if we can't test 
> all mechanisms together with live data?
> 
> 
> thanks


-- 
Thomas Winterstein