[Herefordshire] High Availability Linux

[Chris Bond]

Hi John,

> I confess to having no experience with clusters but, 
> conincidentally, yesterday I read an article in next months 
> (Feb 05) PCPlus about using heartbeat for failover. I'll can 
> email it to you if you like. It sounds as though you are on 
> the right track with heartbeat, drdb, rsync etc.

If you could send the article over that would be great.  Im thinking for
disk sharing to use our SAN instead of drdb as it should be a lot better
than an external scsi array.
 
> For mail, a single DNS entry should suffice as your failover 
> will have the same IP. Secondary MX is a little redundant as 
> most mail servers will keep resending for a few days at least 
> and your HA cluster will allways be, well, available :) 
> Spammers sometimes exploit secondary MX in the hope that 
> there will be less spam checking etc on backup hosts, so 
> maybe use it only if you can keep the mailserver configs in sync.

What I might do is setup an IN A with a low ttl of say 60 then add both ips
to say mailcluster then set the MX preference to that.  I'd rather have two
boxes fed the mail and be able to deal with it rather than waiting to an
"emergency" to test it out.
 
> This all sounds great fun! It would be good to hear of your 
> experiences when the cluster is up and running. It will be 
> really handy to be able to switch off a box for maintenance 
> without interrupting services.

I'll let you know how it goes, should get to play with it in a few weeks.

Kind Regards,
Chris Bond