9800-40 HA update

[richard.greene1]

I have 2 9800-40 controllers in a HA setup. Is it possible to only update one controller at a time so I can switch to the old OS if there is a problem?

[Scott Fella]

Not with HA.  You will end up breaking your HA and your environment.  Depending on the version you have, there is a hitless upgrade option with HA SSO.  Maybe that is something you want to check out.  Keep in mind, when you configure HA SSO, you have to upgrade both as that is a hard requirement.

Hitless Software Upgrade on Catalyst 9800 Series Wireless LAN Controllers - Cisco

[balaji.bandi]

Loog at the upgrade guide : (Patching and installation guide .)

https://www.cisco.com/c/en/us/support/docs/wireless/catalyst-9800-series-wireless-controllers/213915-configure-catalyst-9800-wireless-control.html#anc21

[saravlak]

Hi Richard

I've deployed many 9800-40s and 80s, both back to back RP and site-site RP connection in supported WLC code. There were no issue encountered related to HA. Feel confident, you'll do fine. Use MD release, if not quite comfortable with latest image, however, for any hypothetical reason if you think something doesn't work/fail -in this case deploy another image as backup on it and nice to do it prior to joining the production APs. good luck!

Note: you can upgrade 9800 directly, if its poc or with limited APs directly in short change window. i've done it when i changed my mind at last min based on the requirement.