Files Corrupted While Sitting on Storage Drive

[JCGamble]

Getting prints ready for an exhibition and decided to look back through some Italy images from last year. Copies are sitting on two separate hard drives. To my shock and amazement, the files on both drives are heavily damaged - same jpeg maroon artifacts on the same images. Files are DNGs and last time I checked, all were fine. Guessing that they were damaged prior to backup on both drives.

I thankfully (and luckily) had a spare copy of this entire shoot sitting on one of the two drives in question under a different label and I have since copied it to another two drives. All files seem fine on this copy. I'm trying not to freak out here as I'm worried that two of my backup drives have been somehow corrupted. I've checked a few other shoots on those drives and they seem fine but I'm trying to figure out what went wrong, where was the screw up?

Better yet, what should I do know. Switch out both drives and move the data off of them? Looking for help and advice here as to what to do.

An example of the damaged file appears here:
http://www.jcgamble.com/images/damagedtest.jpg

Please take a look and give me some thoughts and answers.

[peterkrogh]

Joseph,
Well, you need to figure things out quick.

Among the first things to do - validate the existing files, and the try and figure out where the problem came in.

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To validate - send some problem files through the DNG converter.  Does an error get flagged?  If so, that's good - you can try converting the whole archive (send to a drive with enough space on it). Look for patterns in the corruption.  Make a note of problem files and check for backups

Some corruption won't show up in the DNG converter. DNGs made before 1 year ago don't have a validation hash, and will only throw an error warning if the file can't be opened, even though some internal data might be damaged. In the case of these files, I'd suggest creating new DNG files and then look at them with Expression Media (not Bridge, unless you know how to purge all 3 caches).

______

As to finding the source of the problem, if I had to guess, I'd say that the files were most likely damaged in transit (copying from one drive to another).  Do you ever use a validated transfer as outlined in book 2?  This will catch these errors.  It's very difficult to find this sometimes. 

Do you have the new book?  The chapter on backup and validation should give you some insight on how to deal with this problem.

Peter