2.2. Updating Hosts

Use the host upgrade manager to update individual hosts directly from the Red Hat Virtualization Manager. The upgrade manager checks for and notifies you of available host updates, and reduces the time required 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.

Note

The upgrade manager checks only hosts whose status is Up or Non-operational. Hosts in Maintenance are not checked.
On Red Hat Enterprise Linux hosts, the upgrade manager checks for updates to Red Hat Virtualization packages by default. You can specify additional packages for the upgrade manager to monitor for updates using the system configuration value UserPackageNamesForCheckUpdate. Run the engine-config command on the Manager machine. For example:
# engine-config -m UserPackageNamesForCheckUpdate=vdsm-hook-ethtool-options

Warning

For other updates, such as security fixes for the operating system, you must manually update Red Hat Enterprise Linux hosts with yum update as shown in Section 2.3, “Manually Updating Hosts”.
On Red Hat Virtualization Host (RHVH), the upgrade manager uses yum check-update to automatically check for updates to the RHVH image, provided that you registered the host and enabled the Red Hat Virtualization Host 7 repository when installing the host. This repository contains the redhat-virtualization-host-image-update package, which is responsible for updating the image. See Installing Red Hat Virtualization Host in the Installation Guide for
As the RHVH image as a whole is updated, rather than individual packages, manually running yum update for other packages is not necessary. Modified content in only the /etc and /var directories is preserved during an update. Modified data in other paths is completely replaced during an update.
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
You can disable periodic automatic host upgrade checks, using the HostPackagesUpdateTimeInHours configuration value. Automatic upgrade checks are not always needed, for example, when managing the hosts with Satellite. Run the engine-config command on the Manager machine:
# engine-config -s HostPackagesUpdateTimeInHours=0
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.
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

If updating from RHVH 3.6, ensure that you disable the 3.6 repository, and enable the 4.0 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 2.2. Updating Red Hat Enterprise Linux hosts and Red Hat Virtualization Host

  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 InstallationCheck for Upgrade to open the Upgrade Host confirmation window.
  3. Click OK to begin the upgrade check.
  4. If you want to upgrade the host, click Installation Upgrade to open the Upgrade Host confirmation window.
  5. 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 Virtualization environment.

Note

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