CloudStack has a component called HighAvailabilityManager which provides the process for implementing high availability for the infrastructure. CloudStack HighAvailabilityManager provides a well-defined process and works with many other components of CloudStack to provide high availability features in CloudStack. The process of HighAvailabilityManager can be described in three simple steps; they are:
- Investigation: Determining the state of the VM, like finding out whether the VM is up or down or it is impossible to determine its status.
- Fencing: This fences the VM and restricts the usage of network or storage. This is done to prevent any corruption of the VM.
- Start: Turns on the VM instances.