Maintain uptime in the face of required reboots [closed]

view story

http://serverfault.com – I'm researching setting up a dedicated server to run some virtual private servers on (for my friends, hosting some websites, etc.). However, I am stuck as to how to maintain uptime of the guest operating systems in the face of required downtime of the host machine. By required downtime I am mainly thinking of security updates etc. to the Linux kernel which require a reboot to take affect. I have a couple of ideas: migrate all of the guests to a second server for the duration of the reboot. This is posssible, but seems clumsy and would dump twice as VMs on the second server for a while. (HowTos)