[Beowulf] clustering using xen virtualized machines

[Mark Hahn]

> im just wondering now would for instance a head node be of any use running
> virtualized guest os's or does the head node need to not share the hardware
> with other os's

well, the HA-ish motive for VMs has some application to the admin
portions of even a pure HPC clustre.  for instance, your jobs may
execute on bare metal, but there is some appeal to putting various
cluster support services into their own VMs.  for instance, most 
clusters need DHCP and TFTP (eg for PXE) - but that's a fairly 
lightweight service that could be VM'ed.  you'd lose a bit of performance,
but gain the ability to switch physical hosts, can still share physical
hosts with other services, and insulate the service from random insult
like OS/library upgrades.  you can always roll back to a known-good config.
this is not a huge breakthrough, since such services are not all that 
fragile in the first place.  in a sense, part of the value-add of using
a VM is encapsulating a bunch of system settings in a way that's otherwise 
spread across multiple files.

regards, mark hahn.