Beware the unified Cyrus server

[Gary Mills]

If you have:
1) An existing conventional IMAP server, and
2) convert it to a unified murder configuration, with
3) a mupdate slave, and without
4) a mupdatepush entry in cyrus.conf,
it will delete all of the local mailboxes from the mailboxes database.

Note that running without the mupdatepush entry is the recommended
way to start a murder node the first time.  This problem doesn't
happen with a murder backend because there's no mupdate slave.  It
also doesn't happen with a murder frontend because there are no local
mailboxes.  It only happens with a unified front/backend server.
It's particularly annoying because there's no easy way to rebuild the
mailboxes database.

This seems like very dangerous behavior to me, even though it can be
avoided by adding the mupdatepush entry in cyrus.conf.  How can the
mupdate slave be modified to make it safer?

Here are some typical log entries of the server startup.  There seem
to be two copies of mupdate running.  One silently deletes the local
mailboxes.  The other tries to, but can't because they're already gone.

Mar  2 19:10:23 setup01 mupdate[2580]: [ID 974332 local6.error] successful mupdate connection to castor
Mar  2 19:10:23 setup01 mupdate[2580]: [ID 697712 local6.notice] unready for connections
Mar  2 19:10:23 setup01 mupdate[2577]: [ID 974332 local6.error] successful mupdate connection to castor
Mar  2 19:10:23 setup01 mupdate[2577]: [ID 697712 local6.notice] unready for connections
Mar  2 19:10:23 setup01 mupdate[2577]: [ID 104270 local6.notice] synchronizing mailbox list with master mupdate server
Mar  2 19:10:23 setup01 mupdate[2580]: [ID 104270 local6.notice] synchronizing mailbox list with master mupdate server
Mar  2 19:10:23 setup01 mupdate[2577]: [ID 538854 local6.error] MUPDATE: can't delete mailbox entry 'user.cox'
...
Mar  2 19:10:24 setup01 mupdate[2577]: [ID 538854 local6.error] MUPDATE: can't delete mailbox entry 'user.pehn'
Mar  2 19:10:24 setup01 mupdate[2577]: [ID 622122 local6.notice] mailbox list synchronization complete
Mar  2 19:10:24 setup01 mupdate[2580]: [ID 538854 local6.error] MUPDATE: can't delete mailbox entry 'user.wyatt'
Mar  2 19:10:24 setup01 mupdate[2580]: [ID 622122 local6.notice] mailbox list synchronization complete

-- 
-Gary Mills-    -Unix Support-    -U of M Academic Computing and Networking-