ESXi Memory Reservation

[as900w]

I assign 4 GB memory for a VM.

But, I don't have configure Memory reservation. It's 0.

If power on the VM.

Where does the virtual machine get memory?

Physical Memory or VMkernel swap?

My ESXi Server have free memory.

If I configure Memory Reservation to 4 GB.

Can improve the performance of virtual machines?

[IRIX201110141 · Accepted solution]

As long as your Host have enough free memory all mem for your VM comes from there. If the host runs out of resources it depends on how fast this happens.

- Host always creates a swap file for every VM when powering on

- Balloning trough VMware Tools within the Guest

- Host can compress Memory

- In the old days there was also TPS (Transparent page sharing)

A Memory reservation

- Reduce the size of the VM swap file the Hosts creates with VM powered on

- Ensure that your VM have that resources even if the host runs out of memory

It takes no effect on performance as long the host have enough for all of your VMs.

Regards,

Joerg