[Condor-users] Can VM borrow RAM from other VMs in the same computer?

[Juli Céspedes i Capdevila <juli.cespedes@xxxxxxx>]

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Hi,

I'm facing a situation where some of my users are trying to run huge
programs on a single VM, and after careful examination I've realised
that those programs require huge amounts of memory (well, in the range
of 5-7 GB).

One of them is submitting jobs only to the biggest computers we have,
each with two dual core processors, that Condor offers as 4 Vitrual
Machines: vm1@xxxxxxx vm4@jane. Since the computer has 8GB of RAM, each
VM is assigned about 2GB.

When more than one of these big jobs is run on a single physical machine
they never complete, and after a few hours jane is paginating and no
computation is done. After 4 days we have to abort the job.

But if just one of the VMs jane is busy performing the jobs, they
complete after one day or less.

I've been unable to find that info on the documentation, so my question is:
Do VMs on a single node have a reserved amount of memory (as shown on
condor_status output), or do they ask for memory as needed and receive
it if available?

Best Regards
- --
~      Juli Céspedes i Capdevila
~              IT Dept.
ICFO-The Institute of Photonic Sciences
~    Mediterranean Technology Park
~        Av Canal Olimpic s/n
08860 Castelldefels (Barcelona), Spain
~        T: (+34) 93 553 4102
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