DAT and 8mm drives did prove to be the most temperamental (e.g. the drive would claim it needed cleaning two tapes after being cleaned, or would refuse to surrender the medium it has swallowed etc)

Exactly the problems I was having, with two different brands of drives and all different brands of media.

Of course, we used the DAT drives in such a way that they would back up all night every night, so perhaps we were exceeding their duty cycle. But what's the point of a tape drive if you can't back up every night?

one has to advise backup strategy where there will almost always ba a way to bypass a bad tape

Of course. In our organization, we grandfather ten sets of DLTs. So that at any one time, we can instantly go back to any tape from the last ten days. (And this is just our on-site backups. We also have a set of monthly off-sites.)


(e.g. keeping three most recent total, baseline backups and all incremental backups between them, keeping a copy of recent incremental backups on a separate medium, doing fresh baseline backup whenever major or important change happens).

SCREW THAT. Too much organizational overhead. When disaster strikes, you're never quite sure which tape contains which data. I simply do a full file-by-file backup of everything every night onto one tape. I pencil the date on that tape. The next night, I use the next tape. Simple.

When somebody comes to me and asks to have a file restored, all I need from them is the file name and the date. I find the tape with that date, stick the tape in, grab the file, and I'm done.

Sure, incremental backups allow the backups to finish quicker, but the simplicity and ease of recovery, to me, is worth the extra time and expense of full backups.

And the DLT drives/tapes we're using can handle it, both in terms of duty cycle and capacity. They have been dead-reliable for years now.

The only drawback is that after about a year's worth of over-and-over uses, a given DLT cartridge will need to be replaced. I just wait until a given cartridge reports an error, then I swap a new one in its place.

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Tony Fabris