2.3. Updating Red Hat Enterprise Linux Virtualization Hosts

From Red Hat Enterprise Virtualization 3.6 onwards, you can use the host upgrade manager to update individual hosts. The upgrade manager reduces the time required for host updates by automating the process of putting the host into maintenance mode, updating packages, and bringing the host back up. On large deployments with many hosts, this automated process can save a significant amount of time.
The upgrade manager checks for and notifies you of available updates to the vdsm and vdsm-cli packages by default. You can specify additional packages for the upgrade manager to monitor for updates using the system configuration value UserPackageNamesForCheckUpdate. This value accepts wildcards. Run the engine-config command on the Manager machine. For example: 
# engine-config -m UserPackageNamesForCheckUpdate=qemu-kvm-rhev
The upgrade manager checks for updates every 24 hours by default. You can change this setting using the HostPackagesUpdateTimeInHours configuration value. Run the engine-config command on the Manager machine. For example: 
# engine-config -s HostPackagesUpdateTimeInHours=48

Warning

The upgrade manager only updates vdsm, vdsm-cli, and any other packages added to UserPackageNamesForCheckUpdate. For additional updates, such as security fixes for the operating system, you must manually update the host with yum update as shown in Section 2.4, “Manually Updating Red Hat Enterprise Linux Virtualization Hosts”.
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.
Ensure that the cluster to which the host belongs has sufficient memory reserve in order for its hosts to perform maintenance. If a cluster lacks sufficient memory, the virtual machine migration operation will hang and then fail. You can reduce the memory usage of this operation by shutting down some or all virtual machines before updating the host.

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.

Procedure 2.3. Updating Red Hat Enterprise Linux Virtualization Hosts

  1. Click the Hosts tab and select the host to be updated.
    • If the host requires updating, an alert message under Action Items and an icon next to the host's name indicate that a new version is available.
    • If the host does not require updating, no alert message or icon is displayed and no further action is required.
  2. Click Upgrade to open the Upgrade Host confirmation window.
  3. Click OK to update the host. The details of the host are updated in the Hosts tab, and the status will transition through these stages:
    • Maintenance
    • Installing
    • Up
Once successfully updated, the host displays a status of Up. Any virtual machines that were migrated off the host are, at this point, able to be migrated back to it. Repeat the update procedure for each host in the Red Hat Enterprise Virtualization environment.

Note

If the update fails, the host's status changes to Install Failed. From Install Failed you can click Upgrade again.