Manual Pages  — RECOVERDISK

recoverdisk – recover data from hard disk or optical media

SYNOPSIS DESCRIPTION OUTPUT EXAMPLES SEE ALSO HISTORY AUTHORS BUGS

recoverdisk [-b bigsize] [-r readlist] [-s interval] [-u pattern] [-v] [-w writelist] source [destination]

The recoverdisk utility reads data from the source file until all blocks could be successfully read. If destination was specified all data is being written to that file. 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.

By default it uses block sizes of roughly 1 MB, 32kB, 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:

-b bigsize
	The size of reads attempted first. The middle pass is roughly the logarithmic average of the bigsize and the sectorsize.
-r readlist
	Read the list of blocks and block sizes to read from the specified file.
-s interval
	How often we should update the writelist file while things go OK. The default is 60 and the unit is "progress messages" so if things go well, this is the same as once per minute.
-u pattern
	By default blocks which encounter read errors will be filled with the pattern ‘_UNREAD_’ in the output file. This option can be used to specify another pattern. Nothing gets written if the string is empty.
-v
	Enables nicer status report using ANSI escapes and UTF-8.
-w writelist
	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.

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.

# recover data from failing hard drive ada3
recoverdisk /dev/ada3 /data/disk.img

# clone a hard disk
recoverdisk /dev/ada3 /dev/ada4

# read an ISO image from a CD-ROM
recoverdisk /dev/cd0 /data/cd.iso

# continue reading from a broken CD and update the existing worklist
recoverdisk -r worklist -w worklist /dev/cd0 /data/cd.iso

# recover a single file from the unreadable media
recoverdisk /cdrom/file.avi file.avi

# If the disk hangs the system on read-errors try:
recoverdisk -b 0 /dev/ada3 /somewhere

The recoverdisk utility first appeared in FreeBSD 7.0 .

The original implementation was done by Poul-Henning Kamp <Mt phk@FreeBSD.org> with minor improvements from Ulrich Sp&#246;rlein <Mt uqs@FreeBSD.org>.

This manual page was written by Ulrich Sp&#246;rlein.