Secure deletion on physical spindles is extremely resource heavy especially if someone is deleting a very large drive.

Storing encrypted first does affect performance but it is generally much less and more predictable (doing a big secure delete on a drive inflicts an immediate and unexpected hit on that part of a storage array).

We think encryption is also just a lot more robust. If you don't lay down the data in the first place in readable form on the physical drives, its eliminates a lot of data leakage possibilities.

Best wishes,

Patrick