Hi there,

Unfortunately Cassandra is not supported in ceilometer.

Its not mentioned in the documentation: https://docs.openstack.org/developer/ceilometer/install/dbreco.html#legacy-storage

Observe the repo also: https://github.com/openstack/ceilometer/tree/ffc9ee99c10ede988769907fdb0594a512c890cd/ceilometer/storage

There have been attempts to add a cassandra driver support but patches are abandoned and they are not merged

Take a look at blueprint for the same:

https://specs.openstack.org/openstack/ceilometer-specs/specs/liberty/cassandra-driver.html

https://blueprints.launchpad.net/ceilometer/+spec/cassandra-driver

I hope this answers your question

Thanks, Nish Patwa