There is no reason to Zip or otherwise encode data for the purpose of providing a check on whether or not it is still good. There are multiple levels of checking already in the data CD format. The basic CD format (even for music CDs) has a lot of redundancy, error-correction, etc., and then there is a layer of checking on top of that for data CDs. It is so
difficult
to create a CD with data errors on them that people who are making CD readers (hardware or software) spend a lot of $$ to buy special test disks that have unrecoverable errors in order to test their devices. If your data have gotten corrupted, the hardware or software will know it.
Nope. I can tell you from lots of experience that things go "poof" regardless. The file systems commonly in use are not suitable for archival storage. If you don't have a manifest of every file you have, and a suitable checksum, then you really don't have an archive. What you have is a bunch of files on a disk. A lot of people are going to be unhappy a few decades from now. George On 6/25/07, Bill Mixon <billmi...@worldnet.att.net> wrote:
As I reported some months back, the word from a committee that studied the matter is that the data on any recordable CD will outlast the technology if the CD is stored properly (in case on edge at reasonable temperature and not in bright light). "Outlast the technology" means that the data will still be good when you no longer have a device that can read it. A gold CD might last longer if it's stored on your roof exposed to the elements, but so what? There is no reason to Zip or otherwise encode data for the purpose of providing a check on whether or not it is still good. There are multiple levels of checking already in the data CD format. The basic CD format (even for music CDs) has a lot of redundancy, error-correction, etc., and then there is a layer of checking on top of that for data CDs. It is so difficult to create a CD with data errors on them that people who are making CD readers (hardware or software) spend a lot of $$ to buy special test disks that have unrecoverable errors in order to test their devices. If your data have gotten corrupted, the hardware or software will know it. Of course, if your CD writer is defective, it can produce a CD that it or other units can't read. That should be checked from time to time. But if the CD starts out good, it should stay good. (Data recording densities on all sorts of media--CDs, hard mag disks, mag tapes, etc.--have increased tremendously partly because of advances in making tiny bits and partly because of coding and decoding advances that have made it unnecessary to get all the bits right. Your CD player has a chip in it that can do error-checking and correcting calculations that would have challenged a mainframe 30 years ago.) The main data-format precaution is to use the most popular, non-proprietary data format that will accommodate the data you're trying to store and the future uses you may have for it. If you're really trying to make an archive that will last for decades, count on recopying the data onto new-technology media in a new format every couple of decades, unless you want to keep an ancient computer up and running. -- Mixon ----------------------- You may "Reply" to the address from which this message was sent, but note the following permanent addresses for long-term use: Personal: bmi...@alumni.uchicago.edu AMCS: edi...@amcs-pubs.org, sa...@amcs-pubs.org --------------------------------------------------------------------- Visit our website: http://texascavers.com To unsubscribe, e-mail: texascavers-unsubscr...@texascavers.com For additional commands, e-mail: texascavers-h...@texascavers.com