oVirt 3.1 is currently in beta and compared to 3.0 it adds a several new features. One of the nice new features is glusterfs support. For it intended use it works well but I personally think it needs to be adjusted to for more generic use. The 2 main limits that effect me are. 1) Only oVirt nodes in the same cluster can be used as bricks to create clusters. So you can't add in storage only nodes in the same oVirt cluster as nodes. However you can create a cluster of just gluster only nodes. 2) You can not change what interface / IP gluster uses, it will always use the ovirtmgmt network. This is a weakness as many people have an independent network just for storage and they can't use them with 3.1.
If you can live with these limits then gluster intergration is for you. Before we start you should ask yourself whether you want to use glusterfsover NFS or posix (Native) fs. Both work and are very simlilar in setup but they do work slightly differently. Many prefer the native version and if you are using Fedora 17 with it latest kernal then native (posix) fs actually supports direct IO that will increase the throuput a lot. However I found on CentOS 6.2 nodes NFS ran faster because NFS shares are cached. My testing was over a 1G networks so a faster network will yield different results. Both install methods are pretty much the same I will add notes on there differences.
A quick word about OS. While there are plans to support EL6 and other Linux based distributions, support is currently limited to Fedora 17. However Andrey Gordeev ( http://www.dreyou.org/ovirt/ ) has created EL6 packages. Since Fedora 17 crashes on both my Dells every 10 to 12 hours I use the centos builds right now. Although the CentOS builds work really well there are a few missing features, such as live snapshots. I have done both installs and the steps outlined below work for both.