Recovery of a quick erased disc?

[TurboNerd95]

Thanks for continuing to support this program.

I couldn’t see any mention of this in the manual, so I thought I’d ask here before attempting it. I am wondering if you can use the ECC (either the external file or augmented) to recover the original iso of a rewritable disc that has been accidentally quick erased? By quick erased, I mean that the files/directories have been deleted from view, but the files are still physically written to the disc.

I currently use DVD+RW and BD-RE, which I am able to fully read into an iso after a quick erase. I can then recover all the files (extracting from their known LBA values) using data recovery software (Isobuster). However, other types of optical media, such as CD-RW, are not able to be trivially read back in full: https://www.isobuster.com/tips/quick_erased_optical_discs_what_is_recoverable_and_how.

Thank you

[speed47]

Hello,

The page you linked is quite informative about the difference of behaviour between the "quick erases" of all the different disc types. Indeed if the drive just refuses to read the disc because the firmware detects that the disc is advertised as blank, dvdisaster can't do anything.

However if you have made a separate ecc file from a media, quick erased it, and are still able to extract is as an iso from dvdisaster, I think it may work, depending on the amount of data the quick erase write has done. Possibly not too much as otherwise it wouldn't be quick. Have you tried it? I would be very curious about the results!

[TurboNerd95]

Hi speed47 ,

I’ve finished doing 6 different tests, where I tried to use Dvdisaster's ECC to recover the original iso from a DVD+RW and BD-RW that has been quick-erased.

This functionality seems to work very well for my brand of DVD+RW discs (Disc ID: MKM-A02-00), using either RS02, RS03 augmented and RS03 as a file!

For my BD-RE disc (Disc ID: CMCMAG-CN2-000), I could get RS02, and RS03 external file to work, but RS03 augmented mode would not work for this, as the ecc header couldn’t be found, even with exhaustive search for RS03 selected and adaptive reading mode.

Note: after quick-erasing a disc, windows will prompt you to format the disc either as a live file system or mastered. For some reason, If I did not format the disc for the tests using augmented RS02 or RS03, then dvdisaster CAN fully read back the disc, but it would not be able to find any of the Ecc, even when searching exhaustively. After formatting as a live filesystem, I was then able to locate the ecc in most cases, except BD-RE with augmented RS03. I didn’t need to format the disc when external ecc was used.

Here are some details of the results:

• Verbatim DVD+RW (Disc ID: MKM-A02-00):

  • RS03 as an external file (linear readback):
    • Result: ecc found, iso is fully repaired
  • RS03 augmented (disabled exhaustive search for RS03, linear readback):
    • Result: ecc not found, can't repair
  • RS03 augmented (enabled exhaustive search for RS03, linear readback):
    • Result: ecc found, iso fully repaired
  • RS02 augmented (disabled exhaustive search for RS02, linear readback):
    • Result: ecc found, iso fully repaired

• Verbatim BD-RE (Disc ID: CMCMAG-CN2-000):

  • RS03 as an external file (linear readback):
    • Result: ecc found, iso is fully repaired
  • RS03 augmented (keep defect management, disabled exhaustive search for RS03, linear readback):
    • Result: ecc not found, can't repair
  • RS03 augmented (keep defect management, enabled exhaustive search for RS03, linear readback):
    • Result: ecc not found, can't repair
  • RS03 augmented (keep defect management, enabled exhaustive search for RS03, adaptive readback):
    • Result: ecc not found, can't repair
  • RS02 augmented (disabled exhaustive search for RS02, linear readback):
    • Result: ecc found, iso fully repaired

Some screencaps:

DVD+RW with RS03 as an external file:

DVD+RW with RS03 augmented:

BD-RE with RS02 augmented:

[speed47]

Thanks for the thorough tests, it's very informative! I can probably reference those in the readme, or maybe in an FAQ.

I'm a bit surprised by the RS03 augmented images not working however: if the rest works, they should too. Would you be able to retry at least one "failed" RS03 case with the latest build? It includes some fixes for finding RS03 roots when the metadata is destroyed, and hopefully that's exactly the pitfall you encountered.

The latest build is always available here: https://github.com/speed47/dvdisaster/releases/tag/latest (not yet part of an official tagged release, but it includes all the changes/fixes since the last released version). It should be released soon, as we're transitioning to gtk3, thanks to the work of @pitdicker . If you're able to test this build and report if it worked, that would be great. If it doesn't work either, I would be interested in getting the --verbose logs out of your tries, so maybe I have a chance to reproduce them if needed.

[TurboNerd95]

Thanks for alerting me about the latest build! I have tested and can confirm that the same quick-erased BD-RE 25gb disc augmented with RS03 is able to be fully recovered now.

Repaired sectors: 785 (785 data, 0 ecc)
Good! All sectors are repaired.
Erasure counts per ecc block: avg = 1.0; worst = 1.

Summary of processed sectors:
785 damaged sectors
785 CRC errors
1538264 of 94980096 ecc blocks damaged (785 / 46377 sectors)
all data sectors processed
all crc sectors processed
all ecc sectors processed

Update: I can also confirm that I no longer need to format the blank BD-RE in order for it to find the RS03 ecc.

[speed47]

Awesome! That's excellent news. Thanks for taking the time to confirm it!