Clustering the RMS:
In OpsMgr 2007 SP1, clustering a Root Management Server (RMS) was only supported during the initial deployment of a management group. If you were to install a clustered RMS you needed to do this as the very first thing after deploying the first management server. If you later decided to cluster RMS (after you have deployed agents) the ManagementServerConfigTool would detect every Health Service in the management group and add them to the RMS cluster in the Operational Database. Basically, leaving your management group in a broken state. At this point,you would be forced to restore from backup.
In OpsMgr 2007 R2 we have made some changes to the ManagementServerConfigTool to support adding a new RMS cluster to an existing management group.
Upgrading to SQL 2008:
In OpsMgr 2007 R2 we are supporting a new installation of OpsMgr 2007 on SQL 2008 as well as upgrading your SQL 2005 Server to SQL Server 2008.
For more information on each of these see New R2 Deployment Complex Scenarios (Adding Clustered RMS and Upgrading to SQL 2008)
J.C. Hornbeck | Manageability Knowledge Engineer