SQL Server Database Mirroring and Sharepoint server - gotchas and problem solutions
You may be aware that Database Mirroring is an important High Availability [HA] option available within SQL Server 2005 version. Having this HA option within your Sharepoint farm where the databases are associated to failover, then you must note few issues that might crop up in this case.
Also you should be cautious when you have reporting services involved within this Sharepoint farm, as a server administrator, you must specify integration settings that determine the connection between the SharePoint technology instance and a Reporting Services report server. Also you need to be an administrator on the SharePoint site or farm to configure report server integration, and you must have installed the Reporting Services Add-in that provides the configuration pages. You must also have a target report server that is already configured for SharePoint integrated mode.
So further on the subject recently we have had issues when the Mirror databases are failed over using HIGH AVAILABILITY failover option within database mirroing. Soon I have gone through this TechnetBlog-Sharepoint-DBMirroring post to resolve the issues.