Planning WISM to WISM2

Question

Hello,
I hope my english is comprehensible. I have an environment with 2 WISM (4 logical controller) and about 450 APs. Both WISMs have the same configuration. Now I want to migrate the whole thing on 2 WISM-2. I've designed the following scheme and I would like to have confirmed whether this can work this way. The migration should take place during operations, but single APs can fail at short times.
-First, move all the APs on 3 logic controllers, so that one controller is empty
-then update the firmware of the empty controller from version 7.0.116.0 to 7.0.230.0 (bring the WISM-2 on the same version 7.0.230.0, too)
-export the configuration of the empty WISM and import it on the WISM-2
-updating the firmware version of the WISM-2 to the current version (7.2.x.x)
-then change the APs with older version 7.0.116.0 bit by bit from the 3 WISMs to the new WISM-2 with version 7.2.x.x (if it works)
Is that possible, and to recommend, or is there a better alternative for the migration?

Answer 1

Because upgrading the WiSM-2 FUS takes about 20 minutes, I'd be leaving the WAPs with the WiSM-1 and upgrading the WiSM-2 FUS and the firmware to 7.2.110.0.
Once the WiSM-2 upgrades are complete, swing the WAPs across.
Now I know that by doing it this way, the WAPs will go offline because of the software upgrades from the WiSM-2 but I believe it's better this way because it's the same anyway.   Whether you use the orignal method or not, the WAPs will still reboot.
This changes if, say, you the WiSM-2 in the same code level as the WiSM-1.