Software upgrades

Software upgrades

The Ubuntu OpenStack team maintains the Ceph charms. Before upgrading do check their project’s latest Release Notes for any possible messaging with respect to the Ceph charms as well as the Upgrade notes appendix in this guide.

There are three pieces of software in a Charmed Ceph deployment that can be upgraded:

  1. charms
  2. cluster node operating system
  3. Ceph itself

Providing the cluster is designed to withstand a cluster node going offline (a necessity for upgrading a node’s OS) and still able to service its regular workload, a Charmed Ceph cluster can be upgraded with zero downtime.

Important: The upgrade process for Charmed OpenStack, which includes Ceph, is covered in the OpenStack Charms Deployment Guide under Series upgrade and OpenStack upgrades. It is recommended to read these documents before upgrading your Ceph cluster.

Looking at this in terms of upgrade scenarios helps to clarify the required steps. The previous graphic is also very useful in this context:

Scenarios

#1 - A specific Ubuntu release is desired

Current state:

  • Ubuntu 18.04 LTS
  • UCA bionic-train
  • Ceph Nautilus

Goal state: Ubuntu 20.04 LTS

Upgrade path:

  1. charms to latest stable revision
  2. UCA to bionic-ussuri
  3. Ubuntu to 20.04 LTS

Final result: Ceph Octopus on Ubuntu 20.04 LTS nodes

#2 - A specific Ceph release is desired

Current state:

  • Ubuntu 16.04 LTS
  • UCA xenial-queens
  • Ceph Luminous

Goal state: Ceph Nautilus

Upgrade path:

  1. charms to latest stable revision
  2. Ubuntu to 18.04 LTS
  3. UCA to bionic-rocky
  4. UCA to bionic-stein
  5. UCA to bionic-train

Final result: Ceph Nautilus on Ubuntu 18.04 LTS nodes

The next three sections will go into detail on how to complete each respective upgrade type.