Chapter 10. Backup Strategies

The objective of any backup strategy is first to ensure nothing is lost, and second to verify that it can be restored. The reality is that, while this is achievable, with virtualization, we need two distinct paradigms to make this a reality. As we discussed in our design session, a XenServer host has a privileged VM that looks and feels like Linux but has been completely customized. While applying standard Linux backup strategies to it isn’t a bad idea, they only go part of the way to supporting the “ensure nothing is lost” criterion. This section will cover those missing pieces.

We’ll also touch on what it means to backup a guest VM. While XenServer provides the ability to perform snapshots on running VMs, there are many third-party solutions to manage those snapshots. Unfortunately, many users have discovered that simply having a backup of VMs in snapshot form isn’t sufficient. This is because a VM disk by itself lacks the metadata to define the network, memory, and CPU configuration. As a result, any successful strategy needs to encompass both infrastructure and VM backup.

Frequency of Backup

If you are running a XenServer environment that is actively creating and re-creating VMs, then you should pay particular attention to the metadata topics and create an updated metadata backup after each object is configured. In the event a restore is needed and the configuration is stale, errors will be flagged and additional work will be required to ...

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