Open Stack

Hi All,

What are some "best practices" when it comes to overselling RAM in a
KVM based openstack setup?  For example:

I have 4 nodes with 16 cores & 128 GB RAM each.  If on one of those
nodes I oversell ram 2:1 (256 GB RAM) and the VMs actually use that
much does it just start swapping out pages to disk?

How do all of you handle overselling RAM?

Thanks,
Sam