OpenStack OverCommit for CPU/MEM

CPU/RAM over commit 설정 및 적용 (compute 노드)

$  grep ^[^#] /etc/nova/nova.conf | grep allocation cpu_allocation_ratio=4.0 ram_allocation_ratio=2.0 $ systemctl restart openstack-nova-compute.service

https://docs.openstack.org/arch-design/design-compute/design-compute-overcommit.html

아래와 같이 오픈스택 문서상에는 CPU ratio는 16:1, 메모리는 1.5:1이 default라고 되어 있다.

OpenStack Docs: Overcommitting CPU and RAM

 

OpenStack allows you to overcommit CPU and RAM on compute nodes. This allows you to increase the number of instances running on your cloud at the cost of reducing the performance of the instances. The Compute service uses the following ratios by default: CPU allocation ratio: 16:1 RAM allocation ratio: 1.5:1 The default CPU allocation ratio of 16:1 means that the scheduler allocates up to 16 virtual cores per physical core. For example, if a physical node has 12 cores, the scheduler sees 192 available virtual cores. With typical flavor definitions of 4 virtual cores per instance, this ratio would provide 48 instances on a physical node.