[Users] Ovirt Memory Page Sharing or to less memory

[Alan Johnson]

On Mon, Oct 15, 2012 at 6:51 PM, Mathok <mathok1 at googlemail.com> wrote:

> It is possible to increase the level of memory page sharing on a cluster
> above the 200% with a option and start the vms after that change ? or it is
> possible to deactivate the memory threshold with any option?
>

First, let me be clear that this is complete speculation.  That said,
my interpretation of these features based on how the GUI behaves is that
the Cluster Memory Optimization (CMO) setting changes the default Physical
Memory Guarantee (PMG) on new VMs under the Resource Allocation tab.
 However, you could set that number manually to whatever you want.  I have
been setting it to 1/4 of the Memory Size (MS) on the General tab as a
general rule, but varying it by VM as needed.

So, to restate, when CMO is set to None, PMG=MS when creating a new VM.
 When CMO is set to Server, PMG=MS/150%.  When CMO is Desktop, PMG=MS/200%.
 But you can still set the PMG to any custom value any time the VM is not
running.  That much I am sure of.  What I have not tested is my expectation
that the engine will pile the VMs on the hosts based purely on their the
greater of PMG and actual VM use.  It would be reasonably plausible that
the engine limits VMs on the hosts based on CMO as well as PMG and actual
use, but I just don't know for sure either way.

I would greatly appreciated it if some guru could school me on this point.

_______________
Alan Johnson
alan at datdec.com
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