Upgrading a SQL Server Failover Cluster
SQL Server supports upgrade of the Database Engine and Analysis Services from SQL Server 2000 and SQL Server 2005 failover clusters separately on all failover cluster nodes.
Support details are as follows:
Upgrade is supported both through the user interface and from the command prompt. For more information, see How to: Upgrade a SQL Server Failover Cluster Instance (Setup) and How to: Install SQL Server 2008 R2 from the Command Prompt.
Upgrading from SQL Server 2005 — You can run upgrade from the command prompt on each failover cluster node, or by using the Setup UI to upgrade each cluster node. If Full-text search and Replication features do not exist on the instance being upgraded, they will be installed automatically with no option to omit them.
Upgrading from SQL Server 2000 — Similar to upgrade from SQL Server 2005: You can run upgrade from the command prompt on each failover cluster node, or by using the Setup UI to upgrade each cluster node. Supported for 32-bit scenarios only. Failover cluster upgrades from SQL Server 2000 (64-bit) are not supported. For more information, see Version and Edition Upgrades.
Service pack installation - you must apply SQL Server service packs and patches to SQL Server 2008 failover clusters separately on all nodes.
The following scenarios are not supported in SQL Server 2008:
You cannot migrate from a stand-alone instance of SQL Server to a SQL Server 2008 failover cluster.
Add features to a SQL Server 2008 failover cluster. For example, you cannot add the Database Engine to an existing Analysis Services-only failover cluster.
You cannot downgrade a SQL Server 2008 failover cluster node to a stand-alone instance of SQL Server 2008.
For more information, see Getting Started with SQL Server 2008 R2 Failover Clustering.