XenServer includes a new HA feature. When enabled, it monitors the health of all servers in your XenServer pool. If a server in the pool fails, virtual machines (VMs) running on it restart on another server. If the pool master fails, a new server is promoted to pool master automatically, meaning no downtime for XenServer pool management.
Note: Similar to a physical server that crashes, everything written to disk is available when a VM is restarted.
- Shared storage, including at least one iSCSI or Fibre Channel LUN of size 356MiB or greater — the heartbeat storage repository (SR). The HA mechanism creates two volumes on the heartbeat SR, a 4MiB heartbeat volume used for heart beating and a 256MiB metadata volume used to store pool master metadata to be used in the case of master failover. Note: If you are using a NetApp or EqualLogic SR, then you should manually provision an iSCSI LUN on the array to use for the heartbeat SR.
- A XenServer pool (this feature provides high availability at the server level within a single resource pool).
- Enterprise licenses on all hosts.
Note: MiB means MebiByte (1 MiB equals 1,048,576 bytes)
To configure HA, complete the following procedure:
1. Set up HA by selecting the pool node and selecting the Configure HA tab or Selecting Pool > High Availability from the menu bar.
2. You are present with the Configure HA wizard. Select Next.
3. You are presented with the SRs available for HA.
Note: SRs that are not shared storage and also heartbeat SRs cannot be selected.
Note: Unsupported SRs for HA will state after the Description field “The SR backend does not support the operation (check the SR’s allowed operations)
4. Select Next to continue
5. You are presented with the option to assign restart priorities for VMs that are installed on the heartbeat SR selected.
6. You have the option to choose High, Medium, Low, Best effort and Do not restart for selected VMs. You can also adjust the failover capacity of the VMs in question.
A VM that is not installed on a heartbeat SR does not give you restart or failover capacity options, only VMs designated as agile (VMs installed on the heartbeat SR).
7. You are presented with the Activate HA page summarizing the options selected.
8. Select Finish to activate HA.
9. Select the Logs tab to check the progress.
10. After HA has been enabled, you can check the status of HA by going to the HA tab in XenCenter.
11. You can disable HA by selecting Configure HA and selecting Turn off HA.