Initial Experience with Openstack Nova Cells

In the GEYSER project, we are examining suitable Openstack architectures for our pilot deployments. In an earlier blog post we described different ways to architect  an Openstack deployment mostly focusing on AZ (Availability Zone) and Cells (those were the only options available back in 2013). Much has changed since then and new concepts were added such as regions and host aggregates. Even though Cells have been available since Grizzly they are still considered experimental due to lack of maturity and instability. In this blog post we describe our experience enabling Cells in an experimental Openstack deployment.

Why Cells?

The documentation says that “Cells functionality enables you to scale an OpenStack Compute cloud in a more distributed fashion without having to use complicated technologies like database and message queue clustering. It supports very large deployments”. Although we don’t have a large deployment this is pretty much in line with our requirements for our pilot – a distributed system with a single public API exposed. Comparing with other architectural approaches currently available the one which gets closer to this design are regions, but even then is not desirable as it exposes a public API for each region. Continue reading