ddrescue - data recovery tool



ddrescue − data recovery tool


ddrescue [options] infile outfile [mapfile]


GNU ddrescue is a data recovery tool. It copies data from one file or block device (hard disc, cdrom, etc) 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. Be careful to not specify by mistake an old mapfile from an unrelated rescue.

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 unordered domain mapfile with gaps

−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

−W, −−compare−before−write

omit superfluous writes in rescue mode

−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


execute commands from standard input


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


allow infile and outfile to be the same file

Numbers may be in decimal, hexadecimal, or octal, and may be followed by a multiplier: s = sectors, k = 1000, Ki = 1024, M = 10ˆ6, Mi = 2ˆ20, 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 command line options, I/O errors, etc), 2 to indicate a corrupt or invalid input file, 3 for an internal consistency error (e.g., bug) which caused ddrescue to panic.


Report bugs to bug−[email protected]
Ddrescue home page: http://www.gnu.org/software/ddrescue/ddrescue.html
General help using GNU software: http://www.gnu.org/gethelp


Copyright © 2023 Antonio Diaz Diaz. License GPLv2+: GNU GPL version 2 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.


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.

Updated 2024-01-29 - jenkler.se | uex.se