Infant mortality and longevity of DVD media?

I have a specific question, but a general concern about how long a backup can still be read. I realize that all of the hardware and software is less than 10 years old, but the software files being backed up are often 30 years old. Environment: Pentium III (running W98SE) or Pentium 4 (running WXP) and using GHOST 7.0 as the backup software with C: hard drive under FAT32 file structure. An image file backup made of the C: drive is eventually written to a DVD and within a time period of between one second to one day, another copy of the DVD file is made back to a spare hard drive thereby proving that the DVD can be read. In addition, the MD5 value of the image file was kept and written to the DVD and compared with the MD5 value of the file copied from the DVD (since it takes less time to produce the MD5 value from a hard disk file than from an identical DVD file). Question: How long a period of time should I wait to be sure that infant mortality of the image file on the DVD is no longer a factor? Is one second sufficient? i.e. at present as soon as the DVD is finished being burned and the DVD is ejected, I copy all of the files back to a vacant partition on the hard drive. Question: I am using Fujifilm DVD-R 16X 4.7 GB blanks with an old Pioneer 105 DVD burner. I have not experienced any problems over the past 5 years and I plug the power into the DVD burner ONLY when it is being used - which is 3 or 4 times a year. Should I be using a second DVD drive which only reads a DVD to check on the files which have been burned to the DVD blank? How often should I be reading the files on the DVD to be sure that the files can still be read? Is 5 years the length of time before I should duplicate the files on an old DVD? Or perhaps sooner or perhaps longer? Since I make and keep a monthly backup image file of the C: drive (3 DVDs a year with 4 monthly backup files of 1 GB each), loosing one backup image file would probably not be critical. Question: The dual layer DVD drives and blanks (which hold more than 8 GB) seem to be more than double the cost. Are they just as reliable at this point as the single layer drives and blanks which hold only 4.7 GB? Sincerely yours, Jerome Fine -- If you attempted to send a reply and the original e-mail address has been discontinued due a high volume of junk e-mail, then the semi-permanent e-mail address can be obtained by replacing the four characters preceding the 'at' with the four digits of the current year.