Microsoft® SQL Server® 2008 R2 Service Pack 1 and Cumulative Update package 1 for SQL Server 2008 R2

I will explain the steps how to install SQL Server R2 SP1 & its CU in Cluster environment.

[Microsoft® SQL Server® 2008 R2 Service Pack 1]

http://www.microsoft.com/download/en/details.aspx?id=26727

[Cumulative Update package 1 for SQL Server 2008 R2]

http://support.microsoft.com/kb/2544793/en-us

1. First download the setup files.
2. Take backup of your environment.
3. Go to Passive Node.
4. Install Microsoft® SQL Server® 2008 R2 Service Pack 1 in Passive Node server.
5. Install Cumulative Update package 1 for SQL Server 2008 R2 in Node server .
6. Restart the server
7. Move SQL Service to Upgraded Server and wait for 1 min until SQL Server finish from Upgrade mode
8. then go to Second server and do the same steps

Note : 

1. before install SP 1 & CU make sure Integration Service is started
2. if you get any error just reboot the system and rerun the setup file again