ddrescue man page

ddrescue — data recovery tool

Synopsis

ddrescue [options] infile outfile [mapfile]

Description

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. 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.

Options

-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

ask for confirmation before starting the copy

--command-mode

execute commands from standard input

--cpass=<n>[,<n>]

select what copying pass(es) to run

--delay-slow=<interval>

initial delay before checking slow reads [30]

--log-events=<file>

log significant events in <file>

--log-rates=<file>

log rates and error sizes in <file>

--log-reads=<file>

log all read operations in <file>

--mapfile-interval=[i][,i]

save/sync mapfile at given interval [auto]

--max-slow-reads=<n>

maximum number of slow reads allowed

--pause-on-error=<interval>

time to wait after each read error [0]

--pause-on-pass=<interval>

time to wait between passes [0]

--reset-slow

reset slow reads if rate rises above min

--same-file

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 = 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), safecopy(1).

February 2019 ddrescue 1.24