On Sat, 10 Aug 2002 Jawaid.Bazyar@??? wrote:
> My concern with an approach like that is that it multiplies
> administration. If I have 3 front-end servers, I then have 3 places to go
> to administer frozen mail, 3 efficiency reports to analyze, etc.
But if you have 3 front-end servers sharing a spool, you have ONE point
of failure, and also ONE botttleneck. If you are interested in
scalability (which I think you said originally) you should be aware that
when you keep piling load onto Exim, what runs out first is disc I/O
capacity. Sharing the spool between servers would make this worse, not
better, because they'd all be contending for same disc, and would hold
each other up. For performance reasons, you definitely want to give each
server its own spool.
> And most importantly, if one of the front-ends goes down then any mail in
> its spool will not get processed until that server is restored to
> operation.
Not if you have some means of attaching its disc to a different host.
But make sure you use localhost_number if you plan to do this.
Admin over multiple hosts can be done with scripts. The system I'm
sending this from has 3 hosts. I have some hacked up scripts that do
(for example) log scans over all of them. The config is maintained with
rdist. Etc., etc. (Some sysadmins use syslog for logging from multiple
hosts.)
--
Philip Hazel University of Cambridge Computing Service,
ph10@??? Cambridge, England. Phone: +44 1223 334714.
