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On 08/30/2018 10:19 AM, Eugen Block wrote:
> When does Nova apply its filters (Ram, CPU, etc.)?
> Of course at instance creation and (live-)migration of existing 
> instances. But what about existing instances that have been shutdown and 
> in the meantime more instances on the same hypervisor have been launched?
> 
> When you start one of the pre-existing instances and even with RAM 
> overcommitment you can end up with an OOM-Killer resulting in forceful 
> shutdowns if you reach the limits. Is there something I've been missing 
> or maybe a bad configuration of my scheduler filters? Or is it the 
> admin's task to keep an eye on the load?
> 
> I'd appreciate any insights or pointers to something I've missed.

You need to set your ram_allocation_ratio nova.CONF option to 1.0 if 
you're running into OOM issues. This will prevent overcommit of memory 
on your compute nodes.

Best,
-jay