Re: Clustering mail servers - Cyrus or Courier ?
On Mon, 6 Aug 2001, Charl Matthee wrote:
> On Sun, Aug 05, 2001 at 04:10:13PM +0200, Przemyslaw Wegrzyn wrote:
>
> > I'm looking for good solution for big, scalabale mailserver installation,
> > for 500,000 accounts and more...
> >
> > As for now I think:
> > - sharng NFS-mounted mail storage is not so good idea.
> > - scaling can be done by partitioning mail storage between servers (with
> > a little less avialabilty risk).
> >
Sharing over NFS I would not be too spooked about, all depends more on how
the NFS shares are mounted, and what directory structure you've chosen.
I'm currently testing a new system here, Postfix as SMTP server, and
Courier as IMAP/POP server.. Both authenticate and do lookups through
MySQL, and accesstimes are quite good. With 100k accounts and about 100
mail in the maildir, login times were about 0.6 secs for pop3/imap. With
this setup you also get the benefit of no real user accounts for the
email, all is run as one single user/group. Postfix supports several
different MySQL servers also, so you can set up replication between a
couple of MySQL-servers and then add those to Postfix. Havent checked
Couriers support for that though.
One important thing, really try to distribute your accounts in a manner so
you dont get more than say a thousand accounts in each directory. Ext2 as
a filesystem has it's limitations, but I prefer that for now, as I know
it's well tested and reliable.
For me if I have a user called foobaren and one called fooenbar
they go in
/var/spool/mail/foo/bar/foobaren/
/var/spool/mail/foo/enb/fooenbar/
The quota is the problem in this setup. Courier supports maildirquota, but
not verified yet if Postfix does. Possibly you could solve that by using
maildrop as delivery agent.
Regards
Roger A
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Roger Abrahamsson, Sys/Net Admin, Obbit AB
Phone: (+46)(0)90 133310 Fax:(+46)(0)90 133370
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