Using DVDs for Backups and the Futility Thereof

Early this year I made backups of a friend’s PC hard drive on DVDs (using partimage, my full-partition-backup hammer of choice) and now must recover a file for her.

Each of the seven DVDs has two 2 GB files on it and, on every DVD, the second file is riddled with errors.

Thousands, nay, tens of thousands of errors.

The first file on each DVD is perfect: zero read errors.

I’ve tried them on three different drives and, while the errors vary, the pattern is basically the same.

Tick me right off. I’ve had a PC running ddrescue on ’em for the last few days. I’m hoping that by reading them on various drives, the recovery program can merge the good parts, but I’m not holding out a lot of hope. (Update: worked like a champ. Whew!)

Because I’m that type of guy, I always verify the data when I write a CD or DVD, so I know these were good when they were written. Most of the DVDs seem to be visually OK, but some have dark spots in the dye layer. There aren’t any scratches or defects beyond what you’d expect for a DVD that’s been written once and handled by somebody who’s neurotically careful about that sort of thing: they’re not pristine, but they’re not far from it.

Also because I’m that type of guy, they’re generic no-name DVDs, but so what?

Achtung: use the GNU version of ddrescue, because it’s the one that creates & uses a log file to help retry the errors on different machines. The other non-GNU version doesn’t do that.

Memo to self: next time, record -three- sets of DVDs and store the sets separately.