dvdisaster Version 0.64 (pl2)
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Contents

Overview
Examples and screen shots
Download
Command line mode
·Using the command line
·Creating a medium image
·Generating error correction files
·Scanning the medium for errors
·Recovering a medium image
·Choosing alternative drives and file names
·Performing several actions within one program call
·Command syntax
Questions and Answers
Background information
Imprint

Recovering a medium image

To recover data from damaged media, you must first try to read as much data as possible from it into an image file.
If you use the adaptive reading strategy and point dvdisaster to the name of the error correction file, reading will stop when enough data for recovering the image has been collected - resulting in a major time saving!

user@linux> dvdisaster -r --adaptive-read -e medium.ecc
dvdisaster-0.64pl2 Copyright 2004,2005 Carsten Gnoerlich.
[... remainder of the GPL announcement ...]

Device: /dev/cdrom,  ATAPI DVD+RW 8X4X12 B2K7
Medium: DVD+R, 2224288 sectors, 1 layer(s)

Adaptive reading: Trying to collect enough data for error correction.
Creating new medium.img image.
Repairable: 2.6% (correctable: 0; now reading [0..2224288], size 2224288)
Sectors 57264-57279: Medium Error; Unrecovered read error.
Filling image area [57280..1083504]
[... more descriptions of reading process ...]
Repairable: 100.0% (correctable: 319200; now reading [320304..327065], size 6762)
Sufficient data for reconstructing the image is available.

Then you need the appropriate error correction file, which you have hopefully generated at a time when the medium was still fully readable. Enter:

user@linux> dvdisaster -f
dvdisaster-0.64pl2 Copyright 2004,2005 Carsten Gnoerlich.
[... remainder of the GPL announcement ...]

Opening medium.img: 2224288 medium sectors.

Fix mode: Repairable sectors will be fixed in the image.
    5 repaired sectors: 708225 59850 69825 79800 199500
    6 repaired sectors: 708226 59851 69826 79801 89776 199501
[... more reports on repaired sectors ...]
    5 repaired sectors: 708224 59849 69824 79799 199499
Ecc progress: 100.0%
Repaired sectors: 33264
Good! All sectors are repaired.
Erasure counts per ecc block: avg = 3.3; worst = 7.

The message "Good! All sectors are repaired." confirms that the medium image ("medium.img") has been fully recovered. The repaired image can be handled like an ordinary ". i s o" image. It can be written to a new medium using a suitable CD/DVD recording software.

If uncorrectable sectors remain after this stage, try reading the image again (some hints for re-reading). dvdisaster will try to re-read only the missing sectors, and this might retrieve enough missing sectors for a successful error correction run.

Copyright 2004,2005 Carsten Gn÷rlich.
Verbatim copying and distribution of this entire article is permitted in any medium, provided this notice is preserved.