I need to run a VM appliance that wants access to more RAM than available on the physical host (16GB needed). I understand there are performance penalties, but I plan to run this VM as a background process, and really dont care how long it takes. The guest application simply refuses to run if it does not detect enough RAM available, regardless if it needs that much or not at a given point. (and my experience with VMware workstation says the appliance is not as greedy as it would seem, even though it was hard coded with this memory requirement.)

Is there anyway to tell a Vbox guest to overcommit; or can I make modifications on the host OS that will fool the Vbox host process, by reporting more RAM than actual (with an oversized dedicated swap partition on standby)?

I have Windows7 or Linux available for host OS's, whichever would get the job done.

I am trying to migrate all VMs from VMware Workstation, with this one appliance holding me up. Appliance redevelopment may be required in the end, but I am trying to avoid for now ...

Untested proposal: success and/or stability unknown. Use memory ballooning to increase target guest memory beyond the normal "built in" max at guest creation. Using a Linux host with with memory overcommit features allowed, create several smaller dummy VMs that feed the balloon.

Potential Pitfalls:

  • Linux host may OOM error
  • Vbox might realize it is overcommited and refuse (or will it just trust malloc() or similar)
  • Are you sure VirtualBox even supports what you want, because it sounds based on your description, it does not. – Ramhound Aug 15 '14 at 17:02
  • @Ramhound officially it does not seem to. i am seeking workarounds, or possibly unsupported configuration overrides. – user2097818 Aug 15 '14 at 18:48
  • Software either supports something or it doesn't. As I said based on the description it does not appear virtualBox even supports what you want. – Ramhound Aug 15 '14 at 18:52
  • So you want VirtualBox to use swap space to compensate for missing RAM? I don't think it will let you do that. "Performance penalty" would rather be a performance armageddon. – gronostaj Aug 15 '14 at 21:45

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