Cyrus 2.3 on shared filesystems

[Attila Nagy]

Hello,

There are the following lines in the changelog:
"Added support for "unified" and "replicated" Murders. A Murder no 
longer has to have discrete frontend and backend servers; any one 
"unified" server can both proxy and serve local mailboxes (proxy 
functionality in proxyd and lmtpproxyd has been merged with imapd and 
lmtpd respectively), or all "replicated" servers can serve the same 
mailboxes from a shared filesystem."

I will try to explain this to myself, please correct me, if I'm wrong.

The unified approach seems to be simple. The client no longer has to be 
redirected to the given backend using the proxyd, or lmtpproxyd 
(previously called frontend), instead it can turn to any of the backends 
and the backend will know how to deal with that connection (serve as 
local, or proxy to another backend).

Which confuses me a little is the replicated mode. How does it differ 
from having multiple traditional (no murder) cyrus instances accessing 
the same storage?

Is replicated murder consists of multiple backend server groups which 
has the same mailboxes? So murder will say that user.jsmith is on 
server1 AND server2, instead of just saying it's on server1 OR server2?

So effectively it is the same as having many traditional cyrus instances 
on a shared filesystem, but with the ability to use more shared 
filesystems, so for example mailboxes from a-m will go to storage box 1 
and m-z will go to storage box 2?

If so, could somebody define the "shared filesystem"?
The cyrus webpages say that NFS is a big no-no. The problems are locking 
(I guess it could work on a recent Linux or FreeBSD NFS implementation) 
and different mmap behaviour over NFS.

Anybody have positive experiences with NFS or others?

-- 
Attila Nagy                                   e-mail: Attila.Nagy at fsn.hu
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