MSDN has a new white paper:
Planning and Monitoring SQL Server Storage for Office SharePoint Server: Performance Recommendations and Best Practices
It covers topics such as:
- Database Autogrowth
- Storage settings for the recycle bin
- Using Quota templates
- List performance
- Physical Topology Guidance
- Disk and SAN interfaces
- Network Topology recommendations
- Physical Storage recommendations
- Separating database data files
- Monitoring, Maintaining, and Troubleshooting (which provides some great performance counters that can be used for monitoring)
- Disk and SQL recommended practices
In all it is a great resource. The direct download is here.