ddrescue

Data recovery tool that reads data from damaged block devices.

TLDR

Take an image of a device, creating a log file

$ sudo ddrescue [/dev/sdb] [path/to/image.dd] [path/to/log.txt]

Clone Disk A to Disk B, creating a log file

$ sudo ddrescue --force --no-scrape [/dev/sdX] [/dev/sdY] [path/to/log.txt]

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. 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.

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

COPYRIGHT

Copyright © 2020 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.