Masking physical resource on a VM

[gavinmansell]

I am quite new to Vmware ESX 3 Virtual Infrastructure. I was wondering if it was at all possible to mask the physical resource a VM is allocated...

Could you allocate a VM 512MB of physical RAM but make this appear as 2GB within the OS when a user logs on to the VM?

[avlieshout]

Just allocate 2GB to the vm.

When having multiple vms running the same OS you gain from TPS (Transparant Page Sharing). Where multiple vms that have the same memory blocks only use 1 physical memory block.

See this as a single instance storage. This makes it possible to overcommit memory on your vms where you in fact can give out more memory to your vms than you have physical available in your box.

-Arnim van Lieshout

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[AntonVZhbankov · Accepted solution]

No. You can allocate 2GB for VM, and set memory limit to 512MB. VM will actually see 2GB, but it ESX reclaim 1.5GB via baloon driver.

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[gavinmansell]

Thanks for the replies. So the 'Allocated resource' is what is displayed in the VM, but you can set limits way below this allocation?

[avlieshout]

Gavin,

that's correct.

But you should ask yourself if that is the way you wanna go?

Why give out 2GB and instantly limit the vm to only 512MB?

You could better grant 512MB to the vm with no limits. Whenever you run out of memory you can simply upscale the granted memory.

-Arnim van Lieshout

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Blogging: http://www.van-lieshout.com

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