Bimal,

Thanks for the clarification.  I went so far as to examine the properties of the drive and found that after dropping the snapshot, that available space went up on the drive by exactly the amount shown in the "size on disk" property of the snapshot file.

This was very helpful.  I had abandoned use of the snapshot months ago when it looked like it was consuming the same space as the original.   We had noticed the performance hit in our testing and together with the perceived hit on disk space gave up. 

Dang...  I hate it when I am wrong.

Dave