On Mon, Nov 25, 2019 at 02:29:02PM +1100, Dave Horsfall wrote:
> On Mon, 25 Nov 2019, George Michaelson wrote:
>
> >I just failed with a Sun DAT drive. Cable and card bought online,
> >recognized by the mt command, but all it does is eject tapes.
>
> They're worse than 9-track tapes, and that's saying something :-)
Really? Are we talking about those tapes that looked like reel to reel
audio tapes but bigger? Like this?
https://www.canajunfinances.com/wp-content/uploads/2013/04/9-Track-Tape.jpg
Because those are 1000x more reliable than an exabyte tape, they just
worked. Pretty much no matter what, you can spool up that tape and it
will read. 30 years later it will read.
Exabyte won't read 20 minutes later.
I think that certain amount of the reliability issue, as far as both the tapes and the drives are concerned, has to do with scale. Those 8mm Exabyte tapes (DDS tapes, too) are much thinner and hence more easily damaged than a large 9 track reel. If thin tape in a cartridge gets fouled up past a certain point, forget it, there's no salvaging that cartridge. If open reel tape gets damaged and you really need what's on it you can hope that the mechanism can read past the damaged part (a possibility), or as a last resort you could make a careful splice and then attempt to retrieve the rest of the data.
One of the other issues, totally independent of tape, is the rubber chosen by the manufacturers for the drive belts and rollers. Some rubber, stored properly, will still be in usable shape after twenty or thirty years. The rubber on the rollers of my Sun QIC-150 drive? A goopy mess which rendered the drive useless as well as a tape.
But yeah, about 15 years ago I was asked to retrieve some data from Exabyte 8200 tapes that had been written 10 years prior. I went through three drives and countless hours of frustration just to read a half-dozen tapes with some really important information on them. "Archive format" indeed.
-Henry