Re: Load sharing POP/IMAP/smtp
On Thu, 6 Feb 2003 06:28, Lauchlin Wilkinson wrote:
> does anyone have any good links/info on how to set up a
> loadsharing/redunant mail servers (pop, imap, smtp). At the moment I
> have 1 server doing all three jobs but we are soon going to grow out of
> this arrangment andI have not had any experience with setting up such
> systems.
Load sharing and redundancy are two totally different issues.
If you want redundancy then the best thing to do is get a pair of NFS attached
storage devices running in an an active/standby configuration and have the
SMTP/POP/IMAP servers mounting the storage by NFS and using Maildir storage.
This will cost huge amounts of money.
For load sharing I've got Dell 2650 servers with 2*1.8GHz Xeon CPUs, 4G of
RAM, and 5*72G U160 hard drives (4 in a RAID-5 and a hot-spare) that each run
200,000 email accounts with Qmail for delivery and Courier IMAP and POP
servers.
At the front end I have Perdition for directing the POP and IMAP to the right
server based on LDAP data (NB the current version in Unstable still doesn't
work properly for this - the next version should do it). Also I have front
end Qmail servers which direct the mail to the correct back-end server based
on LDAP.
For typical ISP use you should be able to handle at least 100,000 users for
SMTP, POP, and IMAP on a single box without any significant problems (and
it'll be much easier than installing Perdition etc). I could setup a single
machine to handle 1,000,000 accounts if required, it would be an expensive
machine, but setting up a number of smaller machines with Perdition etc is
also expensive and has management costs too.
--
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