Good reasons to choose Ubuntu for large clusters

[Kristian Erik Hermansen]

I don't know why CentOS would give you any benefit over Ubuntu unless
you were patching the kernel.  For instance, for your cluster, you may
want support for the new Completely Fair Scheduler (CFS).  Ubuntu will
surely include support for CFS in Ubunt 8.04 LTS, due to the kernel
inclusion >= 2.6.23.  CentOS may take a long time to include CFS, and
in fact, may not until RHEL6 comes along.  So, if you want cutting
edge features for your cluster, go with Ubuntu.  Otherwise, I don't
see how CentOS offers anything else over Ubuntu.

Btw, I run 64 CentOS machines in a pseudo-cluster at Cisco.  I
previously had them setup with Ubuntu Edgy, but a decision was made
that some administrators may not understand how to support Ubuntu, and
that most admins are more familiar with Red Hat style administration
instead.  Coincidentally, I passed off the project to an intern, and
he is more familiar with Ubuntu and will be moving to Gutsy in the
next release.  Only a few scripts should need changing and we will
make use of the new kernel features that are useful...
-- 
Kristian Erik Hermansen