[ClusterLabs] Live migration possible with KSM ?

[Strahil Nikolov]

Keep in mind that KSM is highly cpu intensive and is most suitable for same type of VMs,so similar memory pages will be merged until a change happen (and that change is allocated elsewhere).
In oVirt migration is possible with KSM actively working, so it should work with pacemaker.
 

I doubt that KSM would be a problem... most probably performance would not be optimal.
Best Regards,Strahil Nikolov
 
  On Tue, Mar 30, 2021 at 19:47, Andrei Borzenkov<arvidjaar at gmail.com> wrote:   On 30.03.2021 18:16, Lentes, Bernd wrote:
> Hi,
> 
> currently i'm reading "Mastering KVM Virtualization", published by Packt Publishing, a book i can really recommend.
> There are some proposals for tuning guests. One is KSM (kernel samepage merging), which sounds quite interesting.
> Especially in a system with lots of virtual machines with the same OS this could lead to significant merory saving.
> I'd like to test, but i don't know if KSM maybe prevents live migration in a pacemaker cluster.

I do not think pacemaker cares or is aware about KSM. It just tells
resource agent to perform migration; what happens is entirely up to
resource agent.

If you can migrate without pacemaker you can also migrate with pacemaker.
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