ddrescue man page

ddrescue — data recovery tool


ddrescue [options] infile outfile [mapfile]


GNU ddrescue - Data recovery tool. Copies data from one file or block device to another, trying to rescue the good parts first in case of read errors.

Always use a mapfile unless you know you won't need it. Without a mapfile, ddrescue can't resume a rescue, only reinitiate it. NOTE: In versions of ddrescue prior to 1.20 the mapfile was called 'logfile'. The format is the same; only the name has changed.

If you reboot, check the device names before restarting ddrescue. Don't use options '-F' or '-G' without reading the manual first.


-h, --help

display this help and exit

-V, --version

output version information and exit

-a, --min-read-rate=<bytes>

minimum read rate of good areas in bytes/s

-A, --try-again

mark non-trimmed, non-scraped as non-tried

-b, --sector-size=<bytes>

sector size of input device [default 512]

-B, --binary-prefixes

show binary multipliers in numbers [SI]

-c, --cluster-size=<sectors>

sectors to copy at a time [128]

-C, --complete-only

don't read new data beyond mapfile limits

-d, --idirect

use direct disc access for input file

-D, --odirect

use direct disc access for output file

-e, --max-bad-areas=[+]<n>

maximum number of [new] bad areas allowed

-E, --max-error-rate=<bytes>

maximum allowed rate of read errors per second

-f, --force

overwrite output device or partition

-F, --fill-mode=<types>

fill blocks of given types with data (?*/-+l)

-G, --generate-mode

generate approximate mapfile from partial copy

-H, --test-mode=<file>

set map of good/bad blocks from given mapfile

-i, --input-position=<bytes>

starting position of domain in input file [0]

-I, --verify-input-size

verify input file size with size in mapfile

-J, --verify-on-error

reread latest good sector after every error

-K, --skip-size=[<i>][,<max>]

initial,maximum size to skip on read error

-L, --loose-domain

accept an incomplete domain mapfile

-m, --domain-mapfile=<file>

restrict domain to finished blocks in <file>

-M, --retrim

mark all failed blocks as non-trimmed

-n, --no-scrape

skip the scraping phase

-N, --no-trim

skip the trimming phase

-o, --output-position=<bytes>

starting position in output file [ipos]

-O, --reopen-on-error

reopen input file after every read error

-p, --preallocate

preallocate space on disc for output file

-P, --data-preview[=<lines>]

show some lines of the latest data read [3]

-q, --quiet

suppress all messages

-r, --retry-passes=<n>

exit after <n> retry passes (-1=infinity) [0]

-R, --reverse

reverse the direction of all passes

-s, --size=<bytes>

maximum size of input data to be copied

-S, --sparse

use sparse writes for output file

-t, --truncate

truncate output file to zero size

-T, --timeout=<interval>

maximum time since last successful read

-u, --unidirectional

run all passes in the same direction

-v, --verbose

be verbose (a 2nd -v gives more)

-w, --ignore-write-errors

make fill mode ignore write errors

-x, --extend-outfile=<bytes>

extend outfile size to be at least this long

-X, --max-read-errors=<n>

maximum number of read errors allowed

-y, --synchronous

use synchronous writes for output file

-Z, --max-read-rate=<bytes>

maximum read rate in bytes/s


ask for confirmation before starting the copy


select what copying pass(es) to run


initial delay before checking slow reads [30]


log significant events in <file>


log rates and error sizes in <file>


log all read operations in <file>


save/sync mapfile at given interval [auto]


maximum number of slow reads allowed


time to wait after each read error [0]


time to wait between passes [0]


reset slow reads if rate rises above min

Numbers may be in decimal, hexadecimal or octal, and may be followed by a multiplier: s = sectors, k = 1000, Ki = 1024, M = 10^6, Mi = 2^20, etc... Time intervals have the format 1[.5][smhd] or 1/2[smhd].

Exit status: 0 for a normal exit, 1 for environmental problems (file not found, invalid flags, I/O errors, etc), 2 to indicate a corrupt or invalid input file, 3 for an internal consistency error (eg, bug) which caused ddrescue to panic.

Reporting Bugs

Report bugs to bug-ddrescue@gnu.org
Ddrescue home page: http://www.gnu.org/software/ddrescue/ddrescue.html
General help using GNU software: http://www.gnu.org/gethelp

See Also

The full documentation for ddrescue is maintained as a Texinfo manual.  If the info and ddrescue programs are properly installed at your site, the command

info ddrescue

should give you access to the complete manual.

Referenced By

dd_rescue(1), recoverjpeg(1), recovermov(1), safecopy(1).

February 2017 ddrescue 1.22 User Commands