Performance vms vs. Memory Host

[ctanaka]

I had the following experience: had a host with 10 VMs allocated, using 60% of available memory on the host, and presented a very bad performance of VMs.

When increase the physical memory of the host, the performance of VMS improved.

How can you explain the performance bad VM with less memory, although consume only 60%

[mvoss18]

The host may have had 60% active memory but it consumed more. The things you would want to look at are ballooning and swapping. Ballooning is a warning that you are overprovisioning memory for VMs and once you start swapping performance will slow to a crawl.