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32 .Nd recover data from hard disk or optical media
42 utility reads data from the
44 file until all blocks could be successfully read.
45 It starts reading in multiples of the sector size.
46 Whenever a block fails, it is put to the end of the working queue and will be
47 read again, possibly with a smaller read size.
49 It uses block sizes of roughly 1 MB, 64kB, and the native sector size (usually
51 These figures are adjusted slightly, for devices whose sectorsize is not a
52 power of 2, e.g., audio CDs with a sector size of 2352 bytes.
54 The options are as follows:
55 .Bl -tag -width indent
57 Read the list of blocks and block sizes to read from the specified file.
59 Write the list of remaining blocks to read to the specified file if
61 is aborted via SIGINT.
68 option can be used in combination.
69 Especially, they can point to the same file, which will be updated on abort.
72 prints several columns, detailing the progress
73 .Bl -tag -width remaining
75 Starting offset of the current block.
77 Read size of the current block.
79 Length of the current block.
81 Is increased for every failed read.
83 Number of bytes already read.
85 Number of bytes remaining.
90 # recover data from failing hard drive ad3
91 .Dl $ touch /data/lots_of_space
92 .Dl $ recoverdisk /dev/ad3 /data/lots_of_space
95 .Dl $ recoverdisk /dev/ad3 /dev/ad4
97 # read an ISO image from a CD-ROM
98 .Dl $ touch /data/cd.iso; recoverdisk /dev/acd0 /data/cd.iso
100 # continue reading from a broken CD and update the existing worklist
101 .Dl $ recoverdisk -r worklist -w worklist /dev/acd0 /data/cd.iso
103 # recover a single file from the unreadable media
104 .Dl $ touch file.avi; recoverdisk /cdrom/file.avi file.avi
110 command first appeared in
113 Reading from media where the sectorsize is not a power of 2 will make all
115 This is due to the DMA reads being split up into blocks of at most 128kB.
116 These reads then fail if the sectorsize is not a divisor of 128kB.
117 When reading a full raw audio CD, this leads to roughly 700 error messages
122 The original implementation was done by
123 .An Poul-Henning Kamp Aq phk@freebsd.org
124 with minor improvements from
125 .An Ulrich Sp\(:orlein Aq uspoerlein@gmail.com .
127 This manual page was written by
128 .An Ulrich Sp\(:orlein Aq uspoerlein@gmail.com .