In the past, there is no HA solution for SMS database, the only thing you can do is backup for any disaster. The good news is, for System Center Configuration Manager 2007 (SCCM 2007) now has an ability to support clustered SQL Server instance. Unfortunately, the documentation for how to install SCCM 2007 with clustered SQL Server is poor. Here is a walk through for how to install SCCM on clustered SQL server.
1. Install Windows 2003 Cluster
2. Install SQL 2000/2005 Cluster
3. By default, Windows will not register SQL Server virtual name in Active Directory, for successfully installing SCCM 2007 on Clustered SQL Server, you must register it. Go to step 4
4. Run setspn.exe (you can download it from Microsoft download center:http://www.microsoft.com/downloads/details.aspx?FamilyID=5fd831fd-ab77-46a3-9cfe-ff01d29e5c46&displaylang=en) utility as below:
SQLSERVER1 is your SQL Server virtual name
SQLSERVER1.contoso.com is FQDN for SQL Server virtual name
5. Add computer account for installing SCCM 2007 to local administrators group on every SQL cluster node.
6. Add user account for installing SCCM 2007 to local administrators group on every SQL cluster node.
7. Restart computer for installing SCCM 2007, and logon with user account for setup
8. Launch SCCM 2007 installer, conduct a normal setup.
If you have any questions, please let me know.