Checking my understanding of ddrescue
I've used the various tools in Rescue Remix several times to successfully get data back - mostly ddrescue. But I want to check my understanding of this incredible tool.
I understand the basic model. You use ddrescue to create a single image file of the damaged drive onto a working drive of equal or larger size.
My question is about the size of the image that's created. Does the ddrescue image contain only the data that's been used on the damaged drive or the whole thing? For example, if the capacity of the damaged drive is 100MB, but I know that only 20MB has been used, then will the ddrescue image be 20 or 100?
The reason I ask is that as drives continue to get astronomically large in capacity, and crash more often, our recovery efforts will take longer and longer. And we have to keep purchasing larger and larger recovery drives.
Finally, what if the 100MB drive has been completely encrypted? My guess is that the ddrescue image would be 100 in this case.
Experts, set me straight.