The problem is that the OS isn't aware of it, so it can't take advantage of the space savings; and moreover _because_ the OS isn't aware of it, the OS might mak

The problem is that the OS isn't aware of it, so it can't take advantage of the space savings; and moreover _because_ the OS isn't aware of it, the OS might make poor assumptions about data integrity. If there was a way for the OS to a) disable dedup when integrity is desired and b) exploit the space saved by using dedup, then it would be a good idea.