I have a VWLAN physical appliance with these partitions:
You are in Partition B.
Partition A runtime: version => V2_2_1_20
Partition B runtime: version => V2_3_0_09
I want to upgrade to version 2.4.0 and I want to know if the runtime version of the "unused partition (A)" is considered as the source partition of the upgrade process ?
In other words am I upgrading form 2.2.1 to 2.4.0 or from 2.3.0 to 2.4.0 ?
You are correct. vWLAN has two partitions, and the upgrade process will alter the inactive partition. So in your case, you current runtime is V2_3_0_09, and you will upgrade from 2.3.0 to 2.4.0. The upgrade overwrites 2.2.1.
Further, you can check "Maintain Current Configuration?" which will upgrade your 2.3.0 configuration, again overwriting 2.2.1.
I hope this helps.