>A client has asked if data on a disk storage pool is actually erased from >a storage pool when expiration occurs. My intuition is that the space the >file occupies is only marked as available for writing, but I would like to >provide the client a more certain answer. Does anybody have a more >definitive answer?
Only highly specialized software in highly secure areas would do such a thing, if at all. If nothing else, it would be very expensive in terms of performance, if at all possible. It is more than infeasible for a product to attempt to erase the parts of a tape whose data had expired. And, such immediate erasure would invalidate database & storage pool recovery, which depends upon storage pool data remaining intact over a reusedelay. So TSM would not have any reason to do this on a disk any more than on a tape. You should inquire of your client why they believe any system should do such a thing. Reuse of space inherently "erases" old data. Standard practices call for obliteration or physical destruction of media leaving the physical security of a computer site. There's no real point in erasing unused areas of media while the media remains in situ. Richard Sims, BU
