Baber Information: Hard Disk Drives For Mac

The Restore function in Disk Utility makes use of a block copy function that can speed up the copy process. It also makes an almost exact copy of the source device.

External Disk Drive For Mac

When we say 'almost exact,' we don't mean to imply that useful data may get left behind, because that's not the case. What it means is that a block copy copies everything in a data block from one device to the other. The results are almost an exact copy of the original. A file copy, on the other hand, copies data file by file, and while the file data remains the same, the location of the file on the source and destination devices will likely be very different.

Mac Hard Drive

Using a block copy is faster, but it does have some limits that affect when it can be used, the most important being that copying block by block requires that both the source and destination devices be first unmounted from your Mac. This ensures that block data doesn't change during the copy process. Don’t worry, though; you don’t have to do the unmounting. Disk Utility’s Restore function takes care of that for you. But it does mean that neither the source nor the destination can be in use when you use the Restore capabilities.