[CentOS] Linux ate my RAM...

Wed Nov 18 22:00:22 UTC 2015
m.roth at 5-cent.us <m.roth at 5-cent.us>

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.
> 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.
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....