Undelete a DVD-RW?

April 19, 2007 12:52 PM

Data Recovery Filter. I stupidly deleted (about 1 GB worth of) some precious .avi files on a DVD-RW with Toast's 'Quick Erase' feature. Data Rescue II can't find anything, and disk utility won't even mount the DVD-RW disk. (OS 10.4.7) Any way to 'un-screw' the pooch on this one, short of sendning it out to a data mining firm?
posted by rudster to computers & internet (3 comments total)

If you can get access to a Windows machine, give IsoBuster a try. It tries to do a raw read of the data on the disc, which is all still there since you just did a 'quick erase'. Here's their page on recovering data from erased DVD-RWs.
posted by marionnette en chaussette at 1:33 PM on April 19, 2007

google reveals that it really depends on whether you just marked the disc as blank, or actually fully formatted it.

the second result seens to indicate you'd be screwed if it had been a CD, but have a chance with a DVD...

The big exception to all the above is DVD+RW (DVD plus RW). The designers of the format were clever enough to decide that there shouldn't be an erase function for this format at all. After all a full erase only adds to the so called DOW (Disc Over-Write) and thus reduces the quality of the media. If a full erase is truly required by the user then the application software can still simply write a neutral pattern over the complete surface of the disc with the same effect. And as a DVD+RW can have only one track in one session, changing the inner circle structures is not needed either. If there is a track already ... well then there is a track already .. why change that ? If one wants to write new content then the old data can simply be overwritten. Of course this also positively influences background format and other features I won't go in to now. In other words there is no erase command that an application can send.

If a user wants to quick erase a DVD+RW then the application software must be clever enough to simply write some neutral data over file-system structures (e.g. ISO9660 and UDF etc). And in fact that's what most applications do when they quick erase a DVD+RW.

The consequence is that for a DVD drive there still is a track after a quick erase, so this is not blank media, and if there is a track with a length then application software, such as IsoBuster, can send read commands and get data back. And a scan for missing data can yield to positive results.

That site recommends a program called IsoBuster, but they sell it, so they may just be saying that.

Looks like it's PC software and you'd need a paid version to deal with Extraction and inspection of Mac associated files.
posted by tiamat at 1:33 PM on April 19, 2007

damn, too slow.
posted by tiamat at 1:33 PM on April 19, 2007