RECOVERDISK(1) BSD General Commands Manual RECOVERDISK(1)NAMErecoverdisk — recover data from hard disk or optical media
SYNOPSISrecoverdisk [-b bigsize] [-r rlist] [-s snapshot] [-w wlist] special
[file]
DESCRIPTION
The recoverdisk utility reads data from the special file until all blocks
could be successfully read. It starts reading in multiples of the sector
size. Whenever a block fails, it is put to the end of the working queue
and will be read again, possibly with a smaller read size.
By default it uses block sizes of roughly 1 MB, 32kB, and the native sec‐
tor size (usually 512 bytes). These figures are adjusted slightly, for
devices whose sectorsize is not a power of 2, e.g., audio CDs with a sec‐
tor size of 2352 bytes.
The options are as follows:
-b bigsize
The size of reads attempted first. The middle pass is roughly
the logarithmic average of the bigsize and the sectorsize.
-r rlist
Read the list of blocks and block sizes to read from the speci‐
fied file.
-s snapshot
How often we should update the worklist file while things go OK.
The default is 60 and the units is "progress messages" so if
things go well, this is the same as once per minute.
-w wlist
Write the list of remaining blocks to read to the specified file
if recoverdisk is aborted via SIGINT.
The -r and -w options can be specified together. Especially, they can
point to the same file, which will be updated on abort.
OUTPUT
The recoverdisk utility prints several columns, detailing the progress
start Starting offset of the current block.
size Read size of the current block.
len Length of the current block.
state Is increased for every failed read.
done Number of bytes already read.
remaining Number of bytes remaining.
% done Percent complete.
EXAMPLES
# recover data from failing hard drive ad3
touch /data/lots_of_space
recoverdisk /dev/ad3 /data/lots_of_space
# clone a hard disk
recoverdisk /dev/ad3 /dev/ad4
# read an ISO image from a CD-ROM
touch /data/cd.iso; recoverdisk /dev/acd0 /data/cd.iso
# continue reading from a broken CD and update the existing worklist
recoverdisk-r worklist -w worklist /dev/acd0 /data/cd.iso
# recover a single file from the unreadable media
touch file.avi; recoverdisk /cdrom/file.avi file.avi
# If the disk hangs the system on read-errors try:
recoverdisk-b 0 /dev/ad3 /somewhere
SEE ALSOdd(1)HISTORY
The recoverdisk utility first appeared in FreeBSD 7.0.
AUTHORS
The original implementation was done by Poul-Henning Kamp
⟨phk@FreeBSD.org⟩ with minor improvements from Ulrich Spörlein
⟨uspoerlein@gmail.com⟩.
This manual page was written by Ulrich Spörlein.
BUGS
Reading from media where the sectorsize is not a power of 2 will make all
1 MB reads fail. This is due to the DMA reads being split up into blocks
of at most 128kB. These reads then fail if the sectorsize is not a divi‐
sor of 128kB. When reading a full raw audio CD, this leads to roughly
700 error messages flying by. This is harmless.
BSD May 6, 2006 BSD
