Geoff,

> As far as my own experience goes the rules for Firebird remain
> unchanged. What the VM gives it is what it will see, so
> Classic may be better for multiple CPU, Super for single CPU.

I agree.

We have 2 ESX server running in our office and your observation that a
VM should be treated like a physical server is correct.

> One of the things highlighted with the performance testing I
> did was just how much CPU can be taken up by the VM in dealing
> with disk and network access. I would be curious to see
> similar stats from ESX.

The level of CPU for network and disk usage varies based on the
hardware. There are a number of adapters which provide VMWare specific
features which reduce the amount of work that the Host server must do to
route the traffic to the VMs.

Local disk storage (which was only recently supported by ESX) works very
well, and you get near-real (ie. like a physical system) IO performance
from within the VMs, without much any CPU cost.

The one comment I would have about using ESX is that the VMWare iSCSI
function is a notoriously poor performer. In a number of cases, it is
actually better to have the VMs stored on an NFS share (to which access
is restricted to the VM server) on an external storage system.

We are fortunate in that our external storage solution can provide CIFS,
NFS, Fiber Channel and iSCSI storage so that we were able to modify the
setup without too much effort. The fact that we installed dual 10Gb/s
network adapters also helped ;-)


Sean