Red Hat Enterprise Linux hosts use the yum command in the same way as regular Red Hat Enterprise Linux systems. Red Hat Virtualization Host (RHVH) can use the yum command for updates, and to install additional packages and have them persist after an upgrade. It is highly recommended that you use yum to update your systems regularly, to ensure timely application of security and bug fixes. Updating a host includes stopping and restarting the host. If migration is enabled at cluster level, virtual machines are automatically migrated to another host in the cluster; as a result, it is recommended that host updates are performed at a time when the host's usage is relatively low.

Important

Ensure that the cluster contains more than one host before performing an update. Do not attempt to update all the hosts at the same time, as one host must remain available to perform Storage Pool Manager (SPM) tasks.

The cluster to which the host belongs must have sufficient memory reserve in order for its hosts to perform maintenance. Moving a host with live virtual machines to maintenance in a cluster that lacks sufficient memory causes any virtual machine migration operations to hang and then fail. You can reduce the memory usage of this operation by shutting down some or all virtual machines before moving the host to maintenance.

Important

If updating from RHVH 3.6, ensure that you disable the 3.6 repository, and enable the 4.1 repository on the host being updated:

# subscription-manager repos --disable=rhel-7-server-rhevh-rpms
# subscription-manager repos --enable=rhel-7-server-rhvh-4-rpms

Procedure 2.3. Manually Updating Hosts

From the Administration Portal, click the Hosts tab and select the host to be updated.
Click Management Maintenance to place the host into maintenance mode.
- On a Red Hat Enterprise Linux host, log in to the host machine and run the following command:
```
# yum update
```
- On a Red Hat Virtualization Host, log in to the Cockpit user interface, click Terminal, and run the following command:
```
# yum update
```
Restart the host to ensure all updates are correctly applied.
Note
Check the imgbased logs to see if any additional package updates have failed for a Red Hat Virtualization Host. If some packages were not successfully reinstalled after the update, check that the packages are listed in /var/imgbased/persisted-rpms. Add any missing packages then run rpm -Uvh /var/imgbased/persisted-rpms/*.

Repeat this process for each host in the Red Hat Virtualization environment.