let me comment on the “one PC” statement, too:
It is a very wise decision to evaluate the situation via the trial offering, because 20 VMs will put a lot of stress on the system. Depending of what you’ll run inside these VMs, that single CPU may actually be more than enough - but depending on the base hardware, I/O will might kill your performance.
Did you actually mean “one machine” (stressing the difference between server & PC hardware)? A typical PC would not provide enough memory support for all those VMs… two further differences are that server CPUs are more optimized for running parallel tasks and a server base system is targeted for more I/O throughput. So if you are really talking about some PC hardware, I don’t expect much joy when running 20 VMs.
I take it from your final question that these VMs will run SLES, too. There’s usually some baseline of file i/O for every Linux system, be it the host or the guest systems… and so you’ll have a constant read/write traffic going to your disk(s). This keeps your disks (and the controller(s)) rather busy, add some applications trying to actually read significant amounts of data from within different VMs and you’ll see quite some delays because of “i/o waits”.
While we’re at SLES VMs - you might as well look into running those via Xen… all para-virtualized and no extra product needed. I haven’t had to use VMware Workstation in a while - does it still need an open window per VM, or will it let you run the VMs head-less?
I’d be interested to hear more about your system and the corresponding test results - please let me (us) know how things turn out!
PS: With regards to licensing it was already pointed out that we’re the technical folks here - but I nevertheless had a look at SUSE’s web site (Germany) and found two corresponding statements: For X86 systems, you have a license per physical machine (with options for 2, 4, 8 sockets) - “per socket” licenses are only mentioned in the context of Itanium and Power CPUs. And it is stated that you need only one SLES license per physical machine, which covers all virtual SLES machines on that physical server. But the final word on this has to come from SUSE, as there may be different licensing models for different countries, so please contact some SUSE sales staff for details.