I have a production HA FAS2650 with no extra shelf, only the internal shelf with the looped SAS ports on both controllers:
• Controller 1 0a to Controller 2 0b • Controller 1 0b to Controller 2 0a
Now I need to add a new shelf so my question is if I need to power off the cluster to add the shelf as I need to disconnect the SAS loop from the controllers to connect them now to the new shelf IOM A and B. In the official documentation I was not able to find the answer as this only mentions for first time setup or with additional shelfs that use only the shelf to shelf connection.
Almost, the only missing part is what if this is the first shelf to be added and the system is already in production, so I need to bring it down in order to disconnect the SAS from the controllers and connect them to the shelf, or this is full hot add just like adding a shelf to an stack.
As @shop_storage mentioned, you can hot-add the shelf if the shelf and your system meet certain requirements. When hot-adding the shelf you will momentarily see Alerts regarding losing a path to the shelf, this will be resolved once you properly complete the shelf addition.
Here is another document describing the hot-add procedure: