I’m currently in the middle of my employer’s SharePoint migration from 2003 to 2007, and in the process we’re moving to new hardware, new farm structure, and new availability requirements. Something that I’m trying to get a handle on is that Database Mirroring only supports up to 10 databases at a time, and this would be a bare MOSS implementation if you would mirror all databases and keep the out of the box SQL 2005 databases (3 SSP, 1 MySite ContentDB, 1 MOSS Content DB, 2 Central Admin DBs, 1 Index DB, 2 ReportServer DBs). For those implementations that split out their content databases, this would be a significant problem. Here are some links that help to address the debate on what scenarios you should use for your High Availability application.
- Joel Olson has two posts on Replication and High Availability, and where any SharePoint admin / architect should start: Replication and High Availability, Mirroring, Log Shipping, and High Availability Resources
- On Technet, there is an article to plan for your availability requirements: Plan for Availability (Office SharePoint Server)
- Mauro Cardarelli has a brief article on MOSS 2007 and High Availability, mentioning the modes of database mirroring implementation, as well as a link to a Microsoft Article outlining Database Mirroring with Office SharePoint Server and Windows SharePoint Services: MOSS 2007 and High Availability
- The last one is a sample high-level solution utilizing database mirroring provided by Scot Hiller: Database Mirroring in SharePoint 2007 for Disaster Recovery
As for our implementation, we’re currently proceeding with the Database Mirroring approach, since our hardware is already purchased, but there are some other compelling ways to provide seamless high availability posted above.