Place a host into maintenance mode when performing common maintenance tasks, including network configuration and deployment of software updates, or before any event that might cause VDSM to stop working properly, such as a reboot, or issues with networking or storage.

When you place a host into maintenance mode the engine attempts to migrate all running virtual machines to alternative hosts. The standard prerequisites for live migration apply, in particular there must be at least one active host in the cluster with capacity to run the migrated virtual machines.

1. Click Compute and then select Hosts.

2. Select the desired host.

3. Click Management and then select Maintenance.

4. Optionally, enter a Reason for moving the host into maintenance mode, which will appear in the logs and when the host is activated again. Then, click OK.

   The host maintenance Reason field will only appear if it has been enabled in the cluster settings.

5. Optionally, select the required options for hosts that support Gluster.

   Select the Ignore Gluster Quorum and Self-Heal Validations option to avoid the default checks. By default, the Engine checks that the Gluster quorum is not lost when the host is moved to maintenance mode. The Engine also checks that there is no self-heal activity that will be affected by moving the host to maintenance mode. If the Gluster quorum will be lost or if there is self-heal activity that will be affected, the Engine prevents the host from being placed into maintenance mode. Only use this option if there is no other way to place the host in maintenance mode.

   Select the Stop Gluster Service option to stop all Gluster services while moving the host to maintenance mode.

   These fields will only appear in the host maintenance window when the selected host supports Gluster.

6. Click OK to initiate maintenance mode.

7. All running virtual machines are migrated to alternative hosts. If the host is the Storage Pool Manager (SPM), the SPM role is migrated to another host. The Status field of the host changes to Preparing for Maintenance, and finally Maintenance when the operation completes successfully. VDSM does not stop while the host is in maintenance mode.

   Note:

   If migration fails on any virtual machine, click Management and then select Activate on the host to stop the operation placing it into maintenance mode, then click Cancel Migration on the virtual machine to stop the migration.

You must activate a host from maintenance mode before using it.

1. Click Compute and then select Hosts.

2. Select the host.

3. Click Management and then select Activate.

4. When complete, the host status changes to Unassigned, and finally Up.

   Virtual machines can now run on the host. Virtual machines that were migrated off the host when it was placed into maintenance mode are not automatically migrated back to the host when it is activated, but can be migrated manually. If the host was the Storage Pool Manager (SPM) before being placed into maintenance mode, the SPM role does not return automatically when the host is activated.

You may need to remove a host from the Oracle Linux Virtualization Manager environment when upgrading to a newer version.

1. Click Compute and then select Hosts and select the host.

2. Select the host.

3. Click Management and then select Maintenance.

4. Once the host is in maintenance mode, click Remove.

   Select the Force Remove check box if the host is part of a Gluster Storage cluster and has volume bricks on it, or if the host is non-responsive.

5. Click OK.