Openstack only building one VM per machine in cluster, then runs out of resources

Solution 1:

I've recently tracked such an error down to a MariaDB problem (https://jira.mariadb.org/browse/MDEV-25714). In my case, MariaDB is version 10.6.5.

When running placement API in debug mode, its log reveals a message like

"Over capacity for VCPU on resource provider . Needed: 1, Used: 4118, Capacity: 768.0"

but checking the entries in the placement db / allocations table shows that "4118" is the sum of all resources for the resource provided, not only for the CPU class.

The problem results from errors in the DBMS handling the "outer join" with a subquery while retrieving the currently allocated resources.

You might want to run the test described by "Daniel Howard" in that ticket to verify if your version of MariaDB is affected as well - unless, of course, you experience these problems but are not using MariaDB at all.