Virtual IPs
From UGCS
UGCS uses "virtual ip's" for a variety of reasons. A virtual IP is an IP that doesn't necessarily always correspond to the same computer, so it can be used for services that move between machines. An example is the NFS server- nfs.ugcs is 131.215.176.76. Usually, that IP is taken by hestia, but if hestia fails, heartbeat will move it to athena. This way, services can failover without waiting for DNS to update and without breaking other stuff (afs, nfs, etc).
How to set up a second/third IP
- Use the "ip" command to add/remove IP's
ip addr add 131.215.176.xxx/32 dev ethN ip addr del 131.215.176.xxx/32 dev ethN
You can just add these commands in post-up/pre-down in /etc/network/interfaces to automatically start the IPs when the computer boots. Only do this if heartbeat isn't set up yet (heartbeat will do it itself)
Current virtual IP's
- nfs (.76)- usually on hestia, can also be on athena
- afs-a (.81)- permanently on hermes
- afsmail (.82)- permanently on hermes (the last two exist for a failed attempt at doing failover AFS mail volumes)
