Re: [Condor-users] Confused about multiple slots, VM_MAX_NUMBER, and VM_MEMORY !?!

[Matthew Farrellee <matt@xxxxxxxxxx>]

Rob wrote:
> 
> Hello,
> 
> I'd like to understand the concept of multi core PCs (which represent
> themselves as independent slots in the Condor pool), in relation to the
> VMware server for the VM Universe.
> 
> For example, a dual core PC (2 CPUs) with 4 GB RAM appears as
> slot1 and slot2 in the condor_status list of the master and each slot
> gets 2 GB of the total physical RAM.
> 
> What are the effects of VM_MAX_NUMBER and VM_MEMORY?
> Are the values defined with respect to the whole PC, or per slot?
> 
> Should I allow two VMs or just one on a dual core PC?
> I suppose this choice then also effects how much RAM I can assign
> to a VM.....?!?
> 
> Thanks!
> Rob.

The variables apply across the entire machine and really serve as a second level of checks that VM jobs must pass.

You should be safe leaving VM_MAX_NUMBER undefined (or set to 0) and setting VM_MEMORY to however much memory is given to a slot.

I'm actually consider removing these in favor of normal startd policy. For instance, if you have 4 cores and want to run only 2 VMs then you only advertise 2 slots. If you want no VMs to be over 1GB then you only advertise 1GB of memory on the slots. If you want a mix of VMs and jobs to run and want to constrain the VMs more then advertise 2 non-VM slots and 2 VM slots, where normal jobs can run on any of the 4.

Have any thoughts on this?

Best,


matt