Patching during Load Balancing operation

It is possible to patch all participating Working Nodes and the Node Controller of the load balancing system during operation. However, since all participants in the load balancing system must have the same patch level, the following procedure must be followed.

1. Stop all Working Nodes. The Node Controller must still be running.

2. We now want to make one of the terminated Working Nodes the temporary Node Controller.
   

   1. Create a file "force_wn_switch.txt" (content arbitrary, can be empty) in its installation directory.

   2. Start this Working Node. The file "force_wn_switch.txt" is now deleted and the Working Node temporarily takes over as the new Node Controller. The old Node Controller shuts down.

   3. As an alternative to using the file, you can use the entry "Forced to be node controller on next restart" in the context menu of the Working Node in the Control Center.

3. Now patch the old Node Controller (the Working Nodes will then pull the changes later).

4. As soon as you restart the old patched Node Controller, the temporary Node Controller shuts down again.

5. Now restart all the old Working Nodes (including the Working Node that was temporarily acting as a Node Controller and will now be running as a normal Working Node again). This completes the entire procedure.

So you can patch the old Node Controller in peace while a Working Node temporarily takes over its role (at the old patch level). Afterwards, the patched Node Controller takes over again. Meanwhile, the load balancing system was continuously available.