Cyrus replication and failover best pracistes

[Dmitry Ivanov]

	Hello!
Folks, looking through maillist history i saw that many of you are 
running cyrus in rolling replication mode. I am interested in 
configuring cyrus replica to use as a standby imap server, where we can 
switch DNS in case of problems with primary backend. While testing on 
playground I got some problems and several questions appeared, may be 
you can help me to solve this.

1. Is it safe to leave "sync_host:" options in imapd.conf and running 
sync_server (due to record in cyrus.conf) on both master and replica, 
and start only sync_client -r on master server? Or better to have 
different config files for different roles?

2. Is there any way to solve issue when master overwrites messages with 
the same filename on replica (messages that were not synced before 
disaster happened) during syncing back to primary host? "guid_mode: 
sha1" set.

May be some one can describe method of switching between replicated 
backends in production? For now I want to switch DNS and and than 
start/stop sync_client daemon.

Thank you for assistance!

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Dmitry S. Ivanov