dovecot - Jan 2011 - Does dsync handle client-side deletions?

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

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? What mailbox format? You haven't disabled index
files, right?
> 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.
Yes, this should happen.
> 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.

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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