Re: mail server changing machines

["Lucas Albers" <albersl@cs.montana.edu>]

I dealt with this problem recently, my mail server had one of it's raid
disks failed. I had to move it to another machine.
While I powered the machine off to put in a new disk.
I didn't want the downtime required for the reboot and putting in the new
disk.

I use the vserver project to use virtual server images, so it was trivial
to do a full move of the system.
Steps:
Rsync data from vserver1 for virtual host mailserver1 to vserver2.
stop mailserver on vserver1.
Rsync data again, from vserver1 for virtual host mailserver1 to vserver2.
start mailserver1 on vserver2.

Downtime:
10 seconds to stop instance of mailserver1.
30 seconds to sync changes after system shutdown.
10 seconds to start up new vserver instance.

Then the new system comes up with the exact same configuration as the old
system, and mail just starts flowing through it again.
I use this method to cluster webservers/database servers/mail servers.
If you use heartbeat and drbd you can get transparent replication of the
data in realtime, whith automatic failover if the primary server dies.

-- 
--Luke CS Sysadmin, Montana State University-Bozeman