Auto upgrade AP3825i how long , we have 800 units spread across 2 controllers

[Rod_Robertson2]

We are going to upgrade a couple of v5210 in the near future , attached are approx 400 AP's ( for example AP3825i ) to each controller.
After the upgrade I understand the AP's when reconnecting will look for a software update from the new code .

My question is how long will my AP's be in a unstable state as not all 400 will get upgraded at one time ..

What is the best way to upgrade the AP's ..

[Rod_Robertson2]

Gents many thanks for your help , the upgrades went well , we have a few AP's that the onsite guys upgraded manually , the only challange we had was that there was a specific file , smRouting.php which needed to be reinstalled to access cloud based features .

[Ronald_Dvorak]

Remember that if FastFailover is enabled that the APs don't upgrade if they switch to the standby controller - you'd need to either do a controlled upgrade or just reboot the APs via GUI so they reconnect and check for the new AP image.

[Rod_Robertson2]

I have never upgraded a system before .. well years ago previous incarnation of this product ( Siemens ). I plan to upgrade the v5120 units to 9.21.10.005, current version 9.21.01.0179

Are there any obvious "gotya's" ? do i need new licences etc..
Thanks for your help

[Chris_Sherman]

No gotchas with licensing for a minor version upgrade. Only other thing I can think of is that upgrading the box itself takes just long enough(on my 4110s) that you start getting nervous so hang in there. 7-8 minutes maybe? Sounds like you have 2 boxes in high availability so you won't have any downtime due to the actual controller upgrade. Fiercely comb the release notes. I call GTAC once-in-a-while for something I see in there.