Question about hypervisor swapping

Essendon

Quick question guys, say I have a VM in a resource pool with a low memory limit. Will hypervisor swapping occur for this VM if the VM consistently hits that limit or will ballooning be enough to cater for the demand for memory? And what impact does it have on other VM's on the host? Assume no other VM's have a memory limit and the host is not under stress with plenty of memory to go around.

I do realize it's not a good idea to put a limit on a VM's resources.

jmritenour

It's going to be swapping to disk. Ballooning is for reclaiming idle memory, and that happens when the VMkernel is unable to satisfy the resources requested by a VM, ie overcommitted RAM. In this case, a hard limit is set on the amount of RAM a VM, or a group of VMs as the case may be, will have access to. So, once that limit is exceed, the hypervisor is going to swap to disk, regardless of how much RAM is actually available on the host.

Bear in mind, the amount of memory committed to overhead in a VM counts toward the memory limit as well.

Essendon

Cheers for the explanation, helped put things in place. I am going through the vSphere resource management guide and this wasnt clear to me.

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