Problems with load balancing cluster on GFS

[Jens Hoffrichter]

Hallo Klaus,

2008/6/6 Klaus Steinberger <klaus.steinberger at physik.uni-muenchen.de>:

>> I'm seeing some weird behaviour with the pop3 daemon on a GFS HA
>> cluster with load balancing.
>
> I would not advise running cyrus-imapd on top of GFS. GFS is even with the
> best tuning possible very slow regarding small files (the typical load type
> of a cyrus-imapd). GFS runs into heavy locking with that type of load. So
> don't do it.
Thanks for the advice, but currently I am tied to that setup, due that
we are operating on a schedule, and are nearly going live with that.
And I just can't afford to redo everything at the moment. But I will
monitor performance very closely, will have a fallback plan if it just
doesn't do what I expect it to do, and I will start with a low load on
it. If you guys are interested in that setup, I will keep you updated
how the things progress :)

>  Current size of my Imap Server is 2500 users and currently 250 GByte of
> Mailboxes used (growing and growing).
Well, we will be talking about something in the range of above 50k
mailboxes, so a single machine is just out of question. And some sort
of standby will be needed. I didn't do the concept for this system,
though, I'm just the one who has to implement it ;)

> I don't see how to avoid a murder setup if you need more than one machine
> running cyrus-imapd in parallel.
Well, there are other possibilities I have seen, especially together
with perdition and an LDAP server (which we have here anyways). But
that is more in the region of an active-passive setup instead of an
active-active setup. And I must admit that I don't know murder that
well, only that it logs very little into the logfiles when delivering
a mail ;)

I don't think I can easily go away from the current setup I'm working
on, but I will monitor it very closely. As I said in the other mail, I
have solved the problem I had, but the performance is behind my
expectations. So I will need to do some more testing to confirm if I
can go live with that cluster.

Regards,
Jens