The latest version of Red Hat Enterprise Virtualization, RHEV 3.1, includes some significant changes, including an option to migrate storage from one data center to another and a new Web client. Upgrading to RHEV 3.1 is a must for most users of version 3.0 because its updates provide valuable enterprise-class features with minimal disruption.
Currently, the only supported upgrade path to RHEV 3.1 is from version 3.0. There are too many differences between older versions and RHEV 3.1 for a direct upgrade path.
Start the upgrade with RHEV-M
The new features in RHEV 3.1 are all managed from the RHEV Manager (RHEV-M) server. Therefore, you should start by upgrading the RHEV-M host. Only when that has finished should you update other hosts.
It's a good idea to schedule the upgrade during a maintenance window. During the upgrade, some packages will be removed and RHEV-M will not be available. That means you won't be able to manage virtual machines the way you're used to, although the VMs themselves are not changed by the upgrade process and will continue running.
Before starting the upgrade, you'll have to make sure that the RHEV-M host is subscribed to all the required channels. You cannot just run the yum update command to update all packages on the host, because if you do that, all you upgrade to is the latest version of RHEV 3.0. To check the current channel subscriptions, use the rhn-channel -l command. If you haven't upgraded your channels, you won't see the rhevm-3.1 channel. Use the rhm-channel --add --channel=rhel-x86_64-server-6-rhevm-3.1 command to add the 3.1 channel to your repositories (see Example 1). You will need to enter your username and password to complete this process. You can use the username and password that you normally use to log in to the Red Hat Network (RHN) website.
Example 1: Adding the RHEV 3.1 channel to your repositories
[root@rhev ~]# rhn-channel --add --channel=rhel-x86_64-server-6-rhevm-3.1
Username: Enter your username
Password: Enter your password
[root@rhev ~]# rhn-channel -l
In this example, the first command (rhn-channel --add --channel=rhel-x86_64-server-6-rhevm-3.1) is used to add the new RHEV 3.1 repository. Then, the rhn-channel –l command is used to display the current channels, allowing you to confirm that the RHEV 3.1 channel was added.
You will also need to be sure your server is subscribed to the JBoss Enterprise Application Platform Version 6 for the Enterprise Server channel. If you've set up the RHEV-M 3.0 host following the default guidelines, it isn't subscribed to this channel yet. To subscribe your RHEV-M host to this channel, you can use the RHN Web interface or use the rhn-channel command to subscribe the host: rhn-channel --add --channel=jbappplatform-6-x86_64-server-6-rpm.
The actual upgrade procedure itself is performed with the rhevm-setup package. Before starting the upgrade, you'll need to make sure that this package is upgraded as well. To do this, use yum update rhevm-setup. Once this has finished, use the rhevm-upgrade command to start the actual upgrade procedure. This will compare the packages currently installed with the packages on RHN and start the upgrade. The upgrade can take a significant amount of time, and you'll be notified once it has completed.
Once the upgrade has successfully completed, you can log in to the new browser interface, which no longer relies on Internet Explorer. In a subsequent article, read how to manage a RHEV 3.1 environment from the new Web client interface.