Upgrade the standby server to ClearSCADA 2009 R1.2.
Restart the standby server.
Wait for the server to fully synchronize with the main server and go into the standby state.
Shut the main server down. The upgraded standby server will take over as the main server.
Upgrade the previously main server to ClearSCADA 2009 R1.2.
Restart the previously main server. The server will synchronize with the new main server and go into the standby state.
Since R1, R1.1 and R1.2 are compatible, it is generally not necessary to upgrade any of the clients in the system unless you specifically require fixes available in R1.2. See the Release Notes for more information.
To upgrade from a version other than ClearSCADA 2009 R1/R1.1, please refer to the Upgrade Strategy for ClearSCADA 2009 R1. Upgrading to R1.2 follows an identical procedure since R1 and R1.2 are completely compatible.