MOSS 2007 and High Availability
More and more folks continue to refer to their MOSS 2007 implementation as "business critical". While that bodes well for internal portal champions, it also puts pressure on IT to ensure uptime. For those infrastructure team members who are interested in ensuring High Availability with MOSS 2007, there is a whitepaper from Microsoft that I have found very useful. First, there's one catch... it assumes a SQL Server 2005 backend. Why? The solution utilizes the database mirroring feature. For those familiar with database clustering as the prime option for ensuring system uptime, this is a very cool (albeit new) alternative. The document can be found here: Using Database Mirroring with Office SharePoint Server and Windows SharePoint Services
(http://go.microsoft.com/fwlink/?LinkId=83725&clcid=0x409)
Speaking of "High Availability", one of the sections of the whitepaper that I found particularly useful is the definition of HA (versus High Protection or High Performance). Here's the snippet. Since it ultimately affects topology design, it's good to match expectations with delivery...
Database mirroring offers three modes of implementation. The choice you select depends on how you want to handle failover processing.
• High availability This operating mode option allows you to synchronize writing transaction logs to both servers and enables automated failover. For this option to work, you must also have a witness server.
• High protection This option allows you to synchronize writing transaction logs to both servers, but failover is manual. Because automated failover is not part of this option, a witness server is not used.
• High performance This option does not synchronize writing transaction logs to the servers, and therefore offers some performance gains. When using this option, you are just assuming that everything is going to complete successfully on the mirror. This option only allows manual failover, and a witness server is not used.