Hi Jay,

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.

I understand that, the overcommitment works quite well most of the time.

It just has been an issue twice when I booted an instance that had been shutdown a while ago. In the meantime there were new instances created on that hypervisor, and this old instance caused the OOM.

I would expect that with a ratio of 1.0 I would experience the same issue, wouldn't I? As far as I understand the scheduler only checks at instance creation, not when booting existing instances. Is that a correct assumption?

Regards,
Eugen


Zitat von Jay Pipes <jaypi...@gmail.com>:

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

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