On 26 Aug 2006, at 16:09, Paul Dekkers wrote:
Right now, it looks tricky to me to enable replication after failover,
or the replicated machine itself if you're not sure that the
replica is
identical and the sync-processes finished completely: if a message-
file
is in place on machine A (say "7.") but it was not replicated to
machine
B while that one becomes the master, the machine B will create a new
file 7. and both machines consider this file synchronised after that:
also if roles switch back, you have two different (with one isolated)
copies of 7.
As I understand it, this is what replication uuids are for. Not that
I've experimented with this particular case.
Or is it only preferred to use a replica if there is a really serious
crash on the (previous) master?
That's certainly how I view the current system. Until replication is
more reliable, I'd be quite leery of any sort of automatic failover.
It sounds nice to me if I could use heartbeat or (u)carp (/ifstated)
like systems to start and stop a sync_client or sync_server copy of
cyrus (both different cyrus.conf) as soon as the state of the virtual
interface changes, but then it is even more likely that some
replication
process is not finished without an admin even noticing it.
I agree, this is a great goal. I'd be interested in seeing a roadmap
for how to achieve it, including how failback would occur. There's a
lot of opportunity to share operational experience with Cyrus. If
only there was a forum to publish such information...
:wes
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