Removing a host/agent in Oracle’s Grid Control can be unnerving: There are enough dependencies between the agent, the (cluster-)database, the listener, the host and so to make your deleting action an endless sequence if you are following them.
But GC really becomes stubborn if the agent we are about to remove is unavailable: due to the host being down or due to network connection problems. The removal jobs will be submitted successfully, but the targets will simply not vanish.
There’s a solution for both problems: Following a hint from David (thanks a lot), I finally found Metalink paper 454081.1: The quintessence is to execute
as user “sysman” on your grid control repository database. (If you are removing an agent that’s still reachable, stop it before executing this one.) The package might run several minutes, but that’s perfectly okay.
It might be interesting to find out more about the capabilities of mgmt_admin – keep it in mind.