[Dovecot] Doubts about dsync, mdbox, SIS

[Timo Sirainen]

On 2.2.2012, at 13.31, Jan-Frode Myklebust wrote:

>>> "/srv/mailbackup/attachments/c3/17/c317b32b97688c16859956f11b803e3bba434349-057274283bb51f4f917e0000bf34f6ab" is
>>> missing, but there are 205 other copies of this file named
>>> /srv/mailbackup/attachments/c3/17/c317b32b97688c16859956f11b803e3bba434349-* with
>>> identical sha1sum.
>> 
>> All of them have a link count of 2, with the other link being in hashes/
>> directory?
> 
> No, these has link count=207.

OK, so they aren't actual copies, they are links to the same file.

> I don't know what you mean by link being in hashes directory.

If you have e.g. aa/bb/aabbccdd-eeee file, there should be a matching aa/bb/hashes/aabbccdd file.

>> That is most likely related to your troubles. If the dsync runs crash,
>> the result could leave extra files lying around etc..
> 
> If dsync backup is supposed to be a viable backup solution, I think it
> should fail much better. If it see errors on the target side it should
> clear the target and do a full sync. Manually cleaning up after it's
> problems is too much work.

Of course. But if no one gives me enough information to reproduce problems, I can't really fix anything. I don't really have time to spend guessing ways to make it break. I've been using dsync to backup my own mails for over a year, with zero problems.

>>> 	Error: Mailboxes don't have unique GUIDs: 08b46439069d3d4db0490000e671bf84 is shared by INBOX and INBOX

What about:

doveadm mailbox status -u user at domain guid '*'

in source server? in dest server? Does one list show two INBOXes or otherwise duplicate GUIDs? Perhaps this was a bug in v2.0.14..

>>> 	Error: Failed to sync mailbox INBOX.ferie 2006.: Invalid mailbox name
>> 
>> Is this a namespace prefix? It shouldn't be trying to sync a mailbox
>> named this (there's an extra "." suffix).
> 
> I believe it's a folder named "INBOX.ferie 2006.", with the user using
> the namespace separator in the folder name..  I believe dovecot allows
> this, so it should also handle backing it up.

It has never been possible to create such folder via Dovecot. IMAP protocol itself prevents that. "CREATE foo." will end up creating "foo", not "foo." If you manually mkdir that, it's not possible to access the mailbox in any way via Dovecot. Everything will simply fail as:

a select foo.
a NO [CANNOT] Invalid mailbox name