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Friends: I have 3 brief questions about ddrescue. This is the operation that I want to run:

sudo ddrescue -f -n -v -v -v -v /dev/sdi /dev/sdh RescueHD10.log
  1. For me, the output drive "/dev/sdh", is brand new. Does it have to be formatted the same way as the input (i.e., damaged) drive? (In other words, if the input drive is NTFS, should the output also be formatted NTFS?)

  2. The output drive, "/dev/sdh", has to be mounted, correct?

  3. The "-v" signifies verbose. Does it make a difference if it's "-v -v -v -v" versus "-vvvv"?

Thank you all for your help!!

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  1. For me, the output drive "/dev/sdh", is brand new. Does it have to be formatted the same way as the input (i.e., damaged) drive? (In other words, if the input drive is NTFS, should the output also be formatted NTFS?)

No, the cloning process will overwrite whatever is on the target drive anyway.

But the target drive must have at least the same size as the source drive, not one single byte less for the cloning to be successful. This is enough with an MSDOS partition table.

If there is a GUID partition table, GPT, and the target drive is bigger, you must also repair the backup partition table at the tail end of the drive. You can do it with gdisk.

  1. The output drive, "/dev/sdh", has to be mounted, correct?

No, if there are partitions on the target drive, they should not be mounted, when cloning. The same holds for the source drive: No partition should be mounted.

  1. The "-v" signifies verbose. Does it make a difference if it's "-v -v -v -v" versus "-vvvv"?

I am not sure, but info ddrescue talks about further -v's so use that syntax.

  • So if the target device (/dev/sdh) in the example above is larger than the input/damaged device (/dev/sdi), I have to repair the backup partition table? I do that with "sudo gdisk /dev/sdh", press "p" to print, "w" to write and "q" to quit? Would it be better/easier to just format a partition on the target device that is the same size as the input/damaged device? Thanks! And pardon my ignorance! – user584936 Jul 5 '18 at 3:57
  • @user584936, Please notice that this is only relevant for GPT. If you want guidance, you can use the shellscript gpt-fix, which will select suitable commands for gdisk: v, x, e, r, d, w, y, as you can see, if you look at it in a text viewer or editor. – sudodus Jul 5 '18 at 5:12
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  1. The tool is a block copy. You're copying the entire drive so the partition table, filesystem structures and everything will be copied from the source to the destination.

  2. No. Emphatically no. You're about to overwrite it at the block level. If you have a mounted filesystem there you may well introduce unintended corruption. Ensure that the source disk is also unmounted. Neither must be in use.

  3. That depends on the particular command, and unfortunately it's not possible to generalise.

You may want to increase the read/write chunk size; the default is 512 byte chunks which is very small. Try 128KB or even bigger.

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  1. Generally: No.
  2. If you intent to dump the partition to a file (i. e. image) Then you need to mount the target device. But if you intend to dump the source (partition) to a block-device like /dev/sda3 (i. e. another partition) then you must NOT mount the target.
  3. I dunno, just try if -vvvv and -v makes a difference.

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