Cyrus IMAP and MySQL mailboxes (Building load-balancingcluster)]

[stevel at ausics.net]

Not really to Sarah, I came in too late in the thread...

2006/11/17, Sarah Walters <s.walters at its.uq.edu.au>:
> > -----Original Message-----
> > From: info-cyrus-bounces at lists.andrew.cmu.edu
> > [mailto:info-cyrus-bounces at lists.andrew.cmu.edu] On Behalf Of
> > Igor Zhbanov
> > Sent: Friday, 17 November 2006 10:32 AM
> > To: info-cyrus at lists.andrew.cmu.edu
> > Subject: Re: Cyrus IMAP and MySQL mailboxes (Building
> > load-balancing cluster)
> >
> > 2006/11/17, Sarah Walters <s.walters at its.uq.edu.au>:
> > > > > > The main problem is to build a shared storage that can
> > > > survive server
> > > > > > crashes, where mail will be stored.
> > > > >
> > > > > Use a SAN.
> > > > First of all, such SAN must be very reliable itself.
> > Second, it must
> > > > support some kind of global locking mechanism, so several
> > nodes can
> > > > use lock to protect file from simultaneous writing.
> > Third, Cyrus IMAP
> > > > must lock mailboxes, so several instances on different
> > server can work
> > > > with one mailbox without conflicts. Whether Cyrus IMAP
> > use locks or
> > > > assumes that he is the only one who access mail box, I
> > don't know. Can
> > > > it safely access one mailbox from different servers, I
> > don't know too.
> > >


I thought Cyrus IMAP  supported multiple concurrent read/writes to the
maildir?
So, if a fibre connected 2TB SAN array (eg: HP MSA1000) is seen as local
drive to the server, what would be wrong with:

A: smtp server
B: smtp server
C: imap/pop server
D: imap/pop server

a,b and c and d all mount /var/imap and /home off the SAN

a and b collect mail, scan it and then store it in /var/imap
c does what it does best and lets the user get their mail
and if need be just turn on D with same mounted drives, all without
additional software, the chances of 2 concurrent imap/pop sessions on same
account would be in the real world so small.

not overly converse in doing things like this, normally if box cant handle
it we get gutsier server.
currently dl580 with MSA1000 SAN does smtp/imap/pop

> > > A good commercial SAN costs a fortune, but it is very
> > reliable. And did

not that expensive these days