10.0 interaction with vmware

[Ivan Voras]

On 26/08/2014 09:16, Paul Koch wrote:

> How does this work actually work ?  Does it only take back what
> FreeBSD considers to be "free" memory or can the host start taking
> back "inactive", "wired", "zfs arc" memory ?  We tend to rely on
> stuff being in inactive and zfs arc.  If we start swapping, we
> are dead.

Under memory pressure, VMWare's Balooning will cause internal FreeBSD's
"memory low" triggers to fire, which will release ARC memory, which will
probably degrade your performance. But from what I've seen, for some
reason, it's pretty hard to actually see the VMWare host activate
balooning, at least on FreeBSD servers. I've been using this combination
for years and I only saw it once, for a trivial amount of memory. It's
probably a last-resort measure.

Also, VMWare will manage guest memory even without any guest software at
all. It keeps track of recently active memory pages and may swap the
unused ones out.

FWIW, I think ZFS's crazy memory footprint makes it unsuitable for VMs
(or actually most non-file-server workflows...), but I'm sure most
people here will not agree with me :D If you have the opportunity to try
it out in production, just run a regular UFS2+SU in your VM for a couple
of days and see the difference.

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