2008/7/3 Jack <xen(a)tequilasolutions.com>:
I currently run two servers, one for mail, one for web + db, but will
be
expanding in future so a virtual architecture seems a good idea, especially if I can
run the VM's on any of the physical machines on the fly as load / failures dictate.
If you want to be able to failover VMs between hosts, you need the
storage for the virtual disks to either be replicated between all
hosts (drbd, cluster filesystem, etc), or to be stored on a external
device (iSCSI, NFS etc) without that each VM depends on the single
server where its disk resides.