Infant mortality and longevity of DVD media?

I agree. On the other hand, it is painful to wait many minutes for each 1 GB file to be checked (produce the MD5 value) while still on the DVD and then manually check the next 1 GB file. So even if the time was the same to copy or check the file, it is far more convenient to just copy all the files on the DVD to the hard drive at which point I have also verified I can read the complete file. If I then check the file copied from the DVD media (reproduce the MD5 value), I am confident that the file on the DVD is completely valid. Interestingly, reproducing the MD5 value the read speed of the file) and it takes me about the same time to manually scan the original saved MD5 value and the new value and compare them. And I just discovered that the length of the MD5 value is 128 bits (32 hex digits - I had though it was that long but somehow the 32 hex digits always became 32 bits when I though about the size) which should be more than sufficient to confirm that the file I have read with the same size as the original is IDENTICAL to the original. I remember that Tim Shoppa used MD5 values for BZ2 files that were downloaded. Since it is rare for downloads to be corrupted, MD5 is probably the most efficient way to verify that the downloaded file is identical. I agree that it would be better to use some methods to restore the archived file if corruption takes place, but yearly testing should minimize that problem. Plus with a monthly backup image, the file I want to recover is most often on more than a single backup image. Sincerely yours, Jerome Fine