You don't scale email servers by putting the imap servers on an LVS and
have them access the message store mounted on an NFS drive. You will just
transfer the IO bottleneck from the imap servers to the NFS server.
It is done by having multiple imap servers on the back end each handling
parts of your entire message store. This is quite practical to setup now
that server blade technology is commonplace.
You can then have multiple perdition imap/pop proxies redirecting requests
to the different imap servers based on the login name. Now these can be
load balanced via LVS or DNS RR if need be. But granted that perdition is
just a thin protocol app, all you need is just two servers with hearbeat
and failoverd to make sure that your imap front ends are always available.
If you need data redundancy on each mailstore, you can use RAID1, or drbd
whichever suites your fancy.
On Wed, 12 Feb 2003, Reynald I. Ngo wrote:
> At 11:38 AM 2/12/2003 +0800, Andre John Cruz wrote:
>
> Perdition is good but how would you sync user mailboxes? That's
> all our dilemma. {;)
>
> >for POP/IMAP, i think Perdition will be a better choice. Perdition
> >(http://www.vergenet.net/linux/perdition) implements a POP/IMAP proxy
> >(which you can do Linux-HA) and directs the connection to the specific
> >POP/IMAP server for that user.
>
> Totally agree with maildir-based mail servers. NFS is not the way
> to go... this is according to Weitse. Although we're doing this at INFOCOM
> before. {;)
>
> >my personal opinion will be to go for a maildir-based mail server (qmail,
> >postfix, courier, etc.) and have the storage shared as NFS. that way you
> >can have two or more servers with the POP/IMAP service (all sharing via
> >LinuxVirtualServer) accessing the same message store.
>
> ---
> Cheers,
>
> Reynald I. Ngo
>
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