Can you create a hard disk-image of the same size as the target drive with GNU ddrescue?

Question

I'm planning on using GNU ddrescue to create a drive image of my failing 1 TB hard drive. Can I store the image sufficiently on another 1 TB hard drive? I figure the answer would be no because the image file would contain header information which in addition to the disk-image itself should exceed the drive`s capacity (in a perfect world, but perhaps not?).

I would clone the drive, but I'm not sure how to make sure the clone isn't modified when booting up the OS (Windows or Linux).

Answer 1

In a perfect world it should fit, but your educated guess is mostly correct.

The problem with the --sparse option, is that "Not all systems support this. Only regular files can be sparse."

You can pipe ddrescue through gzip to compress the end file on the fly. Examples:

# backup
dd if=/dev/hdx | gzip > /path/to/image.gz

# restore
gzip -dc /path/to/image.gz | dd of=/dev/hdx

note that dd and ddrescue are interchangeable. They produce the same result using different techniques.

Answer 2

I would just clone the entire drive. Assuming the drive hasn't completely been toasted I would use dd_rescue.

fdisk -l to see which drive is which and then someting like the following from a live cd:

dd_rescue /dev/sda /dev/sdb

Assuming /dev/sda is the source (bad drive) and /dev/sdb is the destination.