[Dovecot] Does dsync handle client-side deletions?

[Patrick Schoenfeld]

Hi there,

I'm currently evaluating the idea of a multi-master setup where each
node shall hold a full copy of the mailboxes. Basically the idea is
to use NFS and dsync to keep those copies in sync. So I did some
tests with dsync and ran into a problem. Consider the following
scenario:

1) Location1 and Location2 are in sync
2) A mail gets deleted on Location1 (via IMAP)
3) dsync mirror run to sync the two locations

Expected behaviour:
dsync notices that the mail was deleted on Location1 and also deletes
it on Location2 to get the locations in sync.

What I experience, however, is:
dsync notices that the mail is missing on Location2 and copies it
from Location1 to get the locations in sync.

(At least) In debug mode it will spit a warning:

dsync(test2): Info: INBOX: highest_modseq changed: 8 != 11
dsync(test2): Info: INBOX: Couldn't keep all uids
dsync(test2): Info: INBOX: Ignored 1 modseq changes
dsync(test2): Warning: Mailbox changes caused a desync. You may want to
run dsync again.

Now the question is: Doesn't dsync handle deletions or is there something
I missed? Dovecot version is 2.0.9.

Thanks in advance
and best Regards,

Patrick

Re: [Dovecot] Does dsync handle client-side deletions?

[Patrick Schoenfeld]

Hi,

thanks for the quick response.

On Fri, Jan 21, 2011 at 07:21:44PM +0200, Timo Sirainen wrote:
 On Fri, 2011-01-21 at 16:15 +0100, Patrick Schoenfeld wrote:
 
  1) Location1 and Location2 are in sync
  2) A mail gets deleted on Location1 (via IMAP)
 
 Via Dovecot v2.0 IMAP? 

Yes.

 What mailbox format? You haven't disabled index
 files, right?

Mailbox format is Maildir. I haven't disabled index files, at least not
knowingly. Basically I'm using a default configuration, based on
whats delivered with the Debian snapshot package of dovecot2
(from what I can tell, this is doc/example-config/* in the source
tarball) with the neccessary changes to authenticate against a LDAP
server.
However, from a look at the maildirs I cannot find a main index file as
described in [1], only the two other indexes.

hostname:/var/spool/mail1/test2/Maildir# ls -l *index*
-rw--- 1 vmail root 17408 21. Jan 21:12 dovecot.index.cache
-rw--- 1 vmail root  2080 21. Jan 21:12 dovecot.index.log

Is that normal?

  What I experience, however, is:
  dsync notices that the mail is missing on Location2 and copies it
  from Location1 to get the locations in sync.
 
 This shouldn't happen. Although I've heard that this actually does
 happen randomly and I haven't really debugged it much yet. But it should
 be a rare occurrence, not reproducible.

In my current setup its reproducible.
Note: This is dovecot 2.0 on Debian Lenny.

Best Regards,
Patrick

[1] http://wiki2.dovecot.org/IndexFiles