> Hi Bob. As a long time user of DAT as a backup device I want to put
    > my vote against it...

...I have backups that go back to March of 1994 and some data that goes is dated from a decade before that. I back up everything and never overwrite the old data because DAT tapes are cheap and it is hard to imagine every contingency. There have been several occasions that I've gone back to those very old backups to retrieve something that I never thought I would need again.

The problem with DAT came up the last time I needed something off of an old tape backup. The tape had developed an error and Murphy's law says that the error was in exactly the area that I wanted. I did a quick check of my old DAT tapes and found several that had developed errors. I immediately went out and purchased a CD-R drive that was supported by Dantz Retrospect backup software and spent the next week recovering everything possible from my old DAT tapes. This took over 40 hours of my spare time but I discovered to my dismay that I could only recover about 80% of my oldest data. Everything before 1996 was getting very unreliable. This was only after 3-4 years of storage with almost no use. These tapes were written only once and had been read, at most, 3 times. They were high-quality data grade tapes from Sony and TDK. The DAT drive was an older but highly thought of HP device.

My conclusion is that DAT and I suspect that tape-backup in general is not a good long term backup storage solution. Depending on your needs you are probably going to eventually have the same problems that I had. We are now living in a computerized world and for me the idea of having everything I have ever done online be available for the rest of my life is very appealing. I need a very long term solution if I'm going to accomplish that.

So, I bought a 4x Yamaha CD-R that works with Retrospect. So far, this has worked out very well. It is much faster than the DAT backup solution and the TDK disks are that I use are guaranteed for 100 years. The TDK CD-R blanks are going for about $2.00/disk at my local CompUSA and hold 650 MB uncompressed. Retrospect can do compression which gets me about 1.2 GB per disk. This isn't enough for unattended backups but large enough that incremental backups aren't too painful. Again, my hope is that CD-R is going to be reliable in the very long term. Eventually, we will have DVD-R or its equivalent giving several times the CD density. Only time will tell about the reliability issues of CD-R but I already know that DAT doesn't cut it.

I don't know if any of this is useful to you or your readers but whenever I read about using tape as a backup solution, I get the urge to tell of the problems that I encountered. Those problems seem to become apparent only after several years of use.

    — Jim Bailey

DR. MAC responds. . .
    > I've got more than 60 DAT backup tapes going back 5 years and have
    > never had such a problem.

    > Still, it's a scary thought. Because I'm one of the most paranoid
    > people in the world regarding backups, after reading Jim's letter
    > I've decided to back up to CD-R every so often in addition to my
    > daily DAT tape backups, just in case.
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and Nashville Mac User member Dennis Carney responds too...

Clark:

Thanks very much for the DAT info. I totally believe that info to be true. I have over 200 4mm dat tapes from 1992 and have been through DDS1, DDS2, and DDS3 technology. Probably 3% of my tapes over 2 years old have failed! BUT, if you keep a spare backup of all info ( which anybody in their right mind should do with magnetic tape ) you find that your odds are VERY low that you will have two tapes fail with the same data on both. This lowers the odds to where I can deal with it. Most of all my files are obsolete in less that 1 year anyway and less than 2% of my customers need old data after 2 years. Plus 4-6 years I have had NO calls.

SO,...Dat is so CHEAP, and desktape is so EASY, I'm ok doing two backups.

BUT, the guys making one backup only will eventually get burned BAD.

The world isn't as perfect as we had hoped is it?

I remember in broadcast TV the engineers told me that professional video 1" magnetic tape stored under perfect humidity controlled conditions in the vault would deteriorate some after 2 years, and had to be recopied to maintain its signal level. This should be true in ANY magnetic tape format including Dat4mm.

Uncle Dennis

(Hurry up DVD technology!)

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and Clark responds too. . .
    > I use DAT tapes with Optima's DeskTape software, and the new AIT 50gb tapes too, with no problems. And I make duplicate copies too (even though AIT tapes cost $65 each!).
    > Recopy and check every two years sounds like a good policy though, regardless of the format.
    > People who use ZIP or JAZ for backup should understand that they are subject to similar issues, and some say all such removables are even LESS reliable for backup than tape—so TWO copies of everything and bi-annual 'check and re-copy' for those guys too...
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