6.14. Improving Uptime with Virtual Machine High Availability
6.14.1. What is High Availability?
6.14.2. Why Use High Availability?
- When a host becomes non-operational due to hardware failure.
- When a host is put into maintenance mode for scheduled downtime.
- When a host becomes unavailable because it has lost communication with an external storage resource.
6.14.3. High Availability Considerations
- Power management must be configured for the hosts running the highly available virtual machines.
- The host running the highly available virtual machine must be part of a cluster which has other available hosts.
- The destination host must be running.
- The source and destination host must have access to the data domain on which the virtual machine resides.
- The source and destination host must have access to the same virtual networks and VLANs.
- There must be enough CPUs on the destination host that are not in use to support the virtual machine's requirements.
- There must be enough RAM on the destination host that is not in use to support the virtual machine's requirements.
6.14.4. Configuring a Highly Available Virtual Machine
Procedure 6.36. Configuring a Highly Available Virtual Machine
- Click the Virtual Machines tab and select a virtual machine.
- Click the High Availability tab.
Figure 6.12. The High Availability Tab
- Select the Highly Available check box to enable high availability for the virtual machine.
- Select the storage domain to hold the virtual machine lease, or select No VM Lease to disable the functionality, from the Target Storage Domain for VM Lease drop-down list. See Section 6.14.1, “What is High Availability?” for more information about virtual machine leases.
ImportantThis functionality is only available on storage domains that are V4 or later.
- Select Low, Medium, or High from the Priority drop-down list. When migration is triggered, a queue is created in which the high priority virtual machines are migrated first. If a cluster is running low on resources, only the high priority virtual machines are migrated.