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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:
user@linux> dvdisaster -r
dvdisaster-0.55 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)
Creating new medium.img image.
Sector 57264: Medium Error; Unrecovered read error. Skipping 15 sectors.
Sector 57280: Medium Error; Unrecovered read error. Skipping 15 sectors.
[... more read error reports ...]
Sector 716544: Medium Error; Unrecovered read error. Skipping 15 sectors.
Read position: 100.0% ( 2.4x)
33264 unreadable sectors.
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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-0.55 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.
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If you get the message "Good! All sectors are repaired.", the medium image
("medium.img") has been fully recovered. The image can be transferred to a new
medium using a suitable CD/DVD recording software.
If uncorrectable sectors remain after this stage, enter "dvdisaster -r" again.
dvdisaster will try to re-read the missing sectors, and this might
retrieve enough missing sectors for another successful "dvdisaster -f" run.
Re-reading the medium on another drive might also be worthwhile as well as
performing the second read attempt at the next morning:
Some drives read better while being cold.
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