[Beowulf] clustering using xen virtualized machines

[Mark Hahn]

> Two staff couldn't handle 2k users and 100 of departments, or that much
> hardware.

so you say.  my example is a scaled down version of actual 
numbers of my organization.  of course, much depends on how 
you define "user" (logged in right now or "getent passwd | wc -l"?)
or for that matter how you define staff.

> Answering tickets or emails alone would be overwhelming.
> Building/maintaining the VMs, or training/document/helping the
> departments to build their own VMs is a monumental task in and of
> itself.  A more realistic number is 1 FTE per 4 hpc-using departments.

hah.  good for you!

> I would wager that generalizing and not targeting any particular
> performance aspect will only cause the departments to pool their own
> money and build their own targeted resource, for less money, with a grad
> student and an oreilly book.

there's always some tension between such approaches.  but most HPC PIs
quickly learn that it hurts their research when they lose grad student 
time to cluster admin.  the time consumed by cluster admin has a large
constant factor, and very weak size scaling.

> I find that most users only have time for
> their application workflow or domain-specific coding, not to be system
> programmers making VMs.

I'm not sure why you assume such an approach would expect users 
to build VMs from scratch.  customizing a working vm is in principle
no harder in principle than submitting a job.

> Sorry, I'm not drinking the virtualization/cloud koolaid.  I'd love to

I should say here that I'm not either - it's just a minor extension of 
the existing tools.  clearly more significant than grids and potentially 
more useful and general.