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RECOVERDISK(1)		  BSD General Commands Manual		RECOVERDISK(1)

NAME
     recoverdisk -- recover data from hard disk	or optical media

SYNOPSIS
     recoverdisk [-r rlist] [-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.

     It	uses block sizes of roughly 1 MB, 64kB,	and the	native sector 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 sector size
     of	2352 bytes.

     The options are as	follows:

     -r	rlist
	     Read the list of blocks and block sizes to	read from the speci-
	     fied file.

     -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

SEE ALSO
     dd(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 Sporlein
     <uspoerlein@gmail.com>.

     This manual page was written by Ulrich Sporlein.

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

NAME | SYNOPSIS | DESCRIPTION | OUTPUT | EXAMPLES | SEE ALSO | HISTORY | AUTHORS | BUGS

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