When updating from OM 4.x to OCUM 5.x and installing the new core license, I have had a couple of customers experience their DB's being deleted. I don't remember this being a normal behavior. Is this a bug or is this what normally happens. If it is normal behavior, how is this prevented?
What do you mean by db being deleted ? In Oc 5.0 there are couple of options which are turned from OFF to 90days that will purge the Protection Manager Job history.
This may shrink the db size but I am not sure what you mean by db being deleted.
Also starting OC 5.0 there is only one core license which will enable all features upto 250 nodes likes protection, provisioning and disaster recovery. This will remove all other license that you had during dfm 4.x, but this is something that you shouldn't care about.