Jason,
The only issue with DNS failover is that DNS is cached around the Internet.
Just because you change the dns entry doesn't mean people can see the backup server
for up to 24 hours.
That kind of failover requires the Linux High Availability project:
http://www.linux-ha.org/
Of course having a pool of servers showing the same pages is nice but it will
have its own issues with cookie management across servers, like in PHP applications.
Nothing's perfect.
Herb
----- Original Message -----
From: Jason Humphrey <jasonh (at mark) businessws.com>
To: coba-e (at mark) bluequartz.org
Sent: Wednesday, February 7, 2007 6:03:12 PM GMT-0800
Subject: [coba-e:08772] Possible Back-up soloution?
Hi,
Whenever a server goes offline it takes ages to import last nights cmu's
and after that you have to change the DNS settings. Depending on how
many sites you have you could be at it for ages. I would really like to
find a more practical and efficient way of doing all of this. How does
this sound?
2 identical servers, both with the same sites and users set-up but with
using their own IP address. Rsync all the web & user directories on a
regular bases. Run a primary DNS server (on a 3rd server) using a mysql
database and a script that checks each service is running every Xmins,
when it sees a service down it can change the mysql database setting the
appropriate records to point at the backup server.
Say HTTP access fails; script detects failure, database gets altered,
traffic now goes to back-up machine which would be identical to the primary.
Can anybody see any obvious hole in this plan, or know of a better way
to achieve a similar outcome?
-You would have to set up each new vsite and user twice, bit of a pain
-I think for simplicity if one service fails the all services should
fall over so that when the primary is back online you can just Rsync and
the primary server would be up-to-date
-I guess Rsync would have to use relative paths
(/home/sites/www.example.com/web/) instead of (/home/.sites/34/web/) as
you couldn't guarantee that the site IDs were the same. Is this possible?
-Mysql databases would also need to be copied very often so not to lose
new data, is there anyway to get a mysql to replicate changes to a db
instantly?
Any feedback will be very helpful
Thanks
Jason
--
Herb Rubin
Pathfinders Software
http://www.pfinders.com