:-))

Ok - sorry for the drag
By the way I bought DVD-R's from Tayo Yuden who are "guaranteed " for a 100 year lifespam.

So I'll look out for a new external drive before long ...
whatever the interface, 1TB is going below €100 these days, so what the heck.

Thanks for the help and I'll have a close look at the caves. Alternatively, as my wife is a painter and is experimenting...

Thanks a lot for the information. Still ... "probably in the order of decades" ... how probable is this and how many decades. The reason I'm so persistent is simple: since I began using PC's (start of the 80's) I've lost so many material, learning the hard way to better use backups, that I want to minimize my risk. So I already use mirrored drives (fully mirrored) to avoid as much as possible any loss of data due to HD crashes. In your...

Not really a solution. All those are correct on an "active" drive. I'm talking about a drive where e.g. music files are put. Once the drive is full, it is left in the system to play music from, but never rewritten. After some time (years, I know, but that doesn't cure the problem) written bytes, because of loss of magnetic intensity, are "lost" in that they cannot be read correcdtly anymore. This has nothing to do however with...

When you back up data and leave them (on a hard drive) for a considerable amount of time, chances are that some bytes may get coorupted.
Therefore it is a good idea to rewrite a hared disk with stable data on it every now and then.
So I am looking for a software that rewrites a certain percentage of a drive every day, so that it is rewritten e.g. every 200 days (rewriting 0,5% of the drive every day).

Does anyone know...