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I am trying to recover files from an NTFS volume onto my main HFS+ drive using ddrescue. diskutil list reports the following status:

/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *251.0 GB   disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:          Apple_CoreStorage Macintosh HD            250.1 GB   disk0s2
   3:                 Apple_Boot Recovery HD             650.0 MB   disk0s3
/dev/disk1 (internal, virtual):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                  Apple_HFS Macintosh HD           +249.8 GB   disk1
                                 Logical Volume on disk0s2
                                 A3F34C3D-D681-46E5-AED3-A7B5C4345664
                                 Unencrypted
/dev/disk2 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     FDisk_partition_scheme                        *80.0 GB    disk2
   1:                       0xDE                         115.1 MB   disk2s1
   2:               Windows_NTFS                         79.9 GB    disk2s2
/dev/disk3 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *500.1 GB   disk3
   1:                        EFI EFI                     209.7 MB   disk3s1
   2:                  Apple_HFS Backup #2               499.8 GB   disk3s2

I intend to format and create a directory on Backup #2 to store the image, but for now it's just on my Desktop. However, the command returns an error:

ddrescue -v -n -c /dev/disk2 Desktop/D610/Rescue.img Desktop/D610/Rescue.mapfile

Bad or missing numerical argument

Do I need to specify the number of passes over the drive (e.g, r3)?

  • 1
    try man ddrescue – Ipor Sircer Nov 7 '16 at 21:11
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ddrescue -v -n -c /dev/disk2 Desktop/D610/Rescue.img Desktop/D610/Rescue.mapfile

-c = Number of sectors to copy at a time.

If you specify -c you also need to specify the number of sectors.

Keep in mind that the options are case-sensitive, so if you were aiming for "complete-only" that's actually -C.

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