Single Instance Storage (Block level deduplication)

I'm not sure how you would even go about creating such a service on a storage device. The problem is how do you determine when files are non-unique? md5 isn't accurate enough, file name isn't accurate enough, size is not applicable. It starts to become something that is far more resource intensive, just try running noclone, dedupe or any other software on a PC that is supposed to find duplicate files for you. Its a lot to expect of a system that is optimized to read and write files, not file contents.

I don't believe I have ever come across an enterprise storage system that supports single instance, I'm not aware of many applications that even support this outside of Exchange.