Version: 3.5 Stable

Cluster version and AMI OS version

This document explains how the operating system (OS) of the machine image (AMI) that PhoenixAI Cloud clusters run on relates to the cluster version, and lists the Ubuntu LTS release that each cluster version uses.

How the AMI OS version is determined

Every node in a PhoenixAI cluster is a virtual machine launched from a machine image (AMI) that PhoenixAI builds and publishes. PhoenixAI builds these AMIs from the official Ubuntu images published by Canonical.

The OS version is tied to the cluster version:

Each cluster version is built and validated against one specific Ubuntu LTS (Long Term Support) release. All AMIs published for that cluster version use the same Ubuntu LTS release.
You do not choose the OS version when you create a cluster. It is determined by the cluster version that you select. For details about how cluster versions are numbered, see Version naming.
AMI upgrades within a cluster version (for example, to apply OS security patches or kernel fixes) stay on the same Ubuntu LTS release. Only the patch level of the OS changes. For details about how an AMI upgrade is performed, see PhoenixAI Cluster Upgrade.
Moving to a newer Ubuntu LTS release happens only together with a new cluster version.

Ubuntu LTS release cadence

Canonical publishes a new Ubuntu LTS release every two years. PhoenixAI follows this cadence: new cluster versions move to the next Ubuntu LTS release roughly every two years, so that clusters keep running on an OS release that receives security updates from Canonical.

note

The two-year cadence is a guideline, not a commitment. PhoenixAI may adjust when a cluster version moves to a newer Ubuntu LTS release based on the Ubuntu release schedule, security requirements, and validation results.