Is the Backup Volume Readable?

To just remember to know the format and block measurement of a tape, strive to itemize its desk
of contents. The next command produces the desk of contents of a quantity created with dump:
$ restore tbfy block_size device-name
For instance, to learn the desk of contents of a dump tape (made with a blocking issue of 32) on /dev/rmt/0cbn, problem the next command:
$ restore tbfy 32 /dev/rmt/0cbn
If that works, then the remaining is straightforward. (If not, learn “How Do I Learn This Quantity?” in
Chapter 23.)
Blocking Issue
Typically dump can write in a blocking issue that restore can’t learn. This drawback is normally quite simple to get around. As soon as once more, you want the block measurement in
which the amount was written. Decide the amount’s block measurement as mentioned in
Chapter 23. Let’s assume that the block measurement of the amount is 65536. Use dd to learn
the amount, and pipe the output of dd to dump, giving “-” because of the file argument. This
tells restore to learn its knowledge from normal enter.
# dd if=device-name bs=64k|restore tfy –
Why does this work? The blocking of knowledge whereas writing to a quantity drive really
modifications how the info bodily resides on the amount. The restore command wants
to grasp the blocking format to have the ability to learn the amount. Nonetheless, when you
use dd to learn the info from the amount, the info is put right into a pipe. The dd command successfully units the block measurement of the pipe to 1, permitting restore to make use of any
block measurement when studying it.
Byte-Order Variations
The dump backup format could be very filesystem-specific. If in case you have byte-order variations, the variations of dump and restore are most likely additionally totally different. The best, and
probably the one, factor to do is to discover a system that has the identical working system
because of the one which made the amount. That’s as a result of reversing the byte order might permit
you to learn the dump header however, relying on the dump format, it could render the
restored information ineffective.

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