Chapter 1. Overview
This guide describes how to manage Instance High Availability (Instance HA). Instance HA allows Red Hat OpenStack Platform to automatically evacuate and re-spawn instances on a different Compute node when their host Compute node fails.
The evacuation process that is triggered by Instance HA is similar to what users can do manually, as described in Evacuate Instances.
Instance HA works on shared storage or local storage environments, which means that evacuated instances maintain the same network configuration (static IP, floating IP, and so on) and the same characteristics inside the new host, even if they are spawned from scratch.
Instance HA is managed by the following resource agents:
| Agent name | Name inside cluster | Role |
|---|---|---|
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| Marks a Compute node for evacuation when the node becomes unavailable. |
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| Evacuates instances from failed nodes. This agent runs on one of the Controller nodes. |
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| Releases a fenced node and enables the node to run instances again. |
