Hi'
As i know, you have to do the inventory manually.
But i don't see why you have to do inventory before you erase a tape. Normally ARCserve knows (via its database) where the tapes are placed, if not it could'nt even do a rotation job with more than one device group.
So it's only if you suspect that ARCserve has "forgotten" something or you have placed new tapes in your library (maybe that is what you mean?) or the tapeengine has restartet, you may have to do an inventory. And that inventory has to be manually (as i know)
Best regards