[Dovecot] Replication -- multiple users, three or more servers?

[Rich Wales]

Replying to Timo:

> Everything is the same as in that wiki page, except you need to have
> userdb field override the mail_replica setting. Or I guess you wouldn't
> want to have a default mail_replica at all, so users won't accidentally
> get replicated to wrong place. See
> http://wiki2.dovecot.org/UserDatabase/ExtraFields

OK, thanks.

Is there a debugging option I can specify here to cause Dovecot to generate
more verbose logging output, so I can see exactly what is happening (and what
is not working) when I try to run replication?

In the "Replication" wiki page, you show one example using the string "remote:"
at the start of the "mail_replica" value, and another example starting with
"remoteprefix:".  What is the difference between these?  Or is there a typo
here?  I tried searching the wiki but couldn't find anything explaining this.

The example with a dsync wrapper script seems to be describing a situation
where the first line of text sent to the remote host consists of the user name
(which is read by the wrapper script and passed as a command-line argument to
dsync-server).  Is this what "remoteprefix:" does, in contrast to "remote:"?

In the dsync wrapper script example, is "vmail" in the mail_replica value an
example of a user ID to be used on the remote host?  What user ID is used on
the local host?  I think one reason why my tests so far haven't been working
may be that I'm not sure which user ID is being used on each end, so my SSH
keys aren't being used properly and the connection is failing.

Finally, the "Replication" wiki page mentions the "authorized_keys2" file,
which (AFAIK) is deprecated in the current SSH -- all authorized keys should
be in a single "authorized_keys" file on the target host, right?

Rich Wales
richw at richw.org