Warren Young wrote: > On Nov 18, 2015, at 1:20 PM, Kwan Lowe <kwan.lowe at gmail.com> wrote: >> >> Because of caching, from VMWare's perspective, all Linux memory is >> being "used”. > > Nope. VMware’s memory ballooning feature purposely keeps some of the > guest’s RAM locked away from the kernel. This is where RAM comes from > when another guest needs more physical RAM than it currently has access > to: > > https://blogs.vmware.com/virtualreality/2008/10/memory-overcomm.html > > There are downsides. <snip> > Another, of course, is that oversubscription risks running out of RAM, if > all of the guests decide to try and use all the RAM the host told them it > gave. All of the guests end up being forced to deflate their balloons > until there is no more balloon memory left. <snip> Note that in '09, VMWare was advising us (where I was working at the time) to not go over 2 or 2.5 times real memory.... mark