Re: [condor-users] One vm or two?

[Alain Roy <roy@xxxxxxxxxxx>]

> Thanks for the good advice.  There are some useful tricks in there.
> Unfortunately, though, I don't think it'll do what I need.  When I say
> "big" or "small" jobs, I mean that in terms of memory use, not running
> time.  Creating three equal vms would mean that each has one-third of
> the machine's physical memory, and then no job that requires more than
> that would ever run.  Do I have that right? Or is it possible to assign
> each vm all of the memory, and then use some other strategy to make them
> share it?

Each VM advertises that it has a certain amount of memory, but the virtual 
machine does not normally enforce that you only use that much memory. 
(Though you could set it up that way.)

When your jobs run, you can set the requirements to lie about the memory 
usage. Your big jobs can say:

   Requirements = Memory > 1

Normally Condor fills in this memory requirement, but it will not override 
what you write.

Assuming you don't actually overrun the total free memory on a machine, 
this may work well for you.

To ensure that users don't get it wrong, you may want to make a wrapper for 
condor_submit to help your users submit jobs in a consistent way. That's 
what was done in the document I shared earlier.

-alain


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