Re: QIC2DC cartridges?

Hello James,

Am 15.04.2021 um 00:47 schrieb James H. H. Lampert <jamesl@xxxxxxxxxxxxxxxxx>:

Shuffling tape drives in the "fat" 170 (which currently contains the V4R2 "brains" of our 40s) might be barely practical, were the need to arise, since it is by its nature a rarely-used "swing" machine, and is at floor level, mounted on a custom dolly.

Shuffling tape drives in the "slim" 170 (V4R4) is not practical, as it is an active development box, and is on an eyeball-high shelf.

With all due respect, but if you need progress to be made, sometimes you need to take action. Practical or not, if you're running out of options, sometimes impractical solutions are better than no solution at all.

Here is where it gets interesting: last week, shortly after the successful "brain transplant," I did a *successful* GO SAVE 21 from the V4R2 "brains" to the one QIC2GB tape we have that *didn't* snap its drive belt.

On a side note: This is not a guarantee that you'll be able to re-read the data in an emergency. Besides that, see my notes on replacing drives with provenly more reliable tape technology. However impractical this might seem but it's a lot better than losing all data because the not-snapped cartridge worked but maybe contaminated the drive head with rubber residue, making a restore impossible for even older cartridges with older backups.

Today, I tried it with the new QIC2DC tapes. V4R2 wouldn't recognize a QIC2DC format, but it *would* recognize a QIC2GB format, and a GO SAVE 21 worked just fine, except for one small issue: it required *BOTH* tapes.

Clearly, a QIC2DC is shorter than an actual QIC2GB (Unfortunately, neither QIC2DC tapes nor QIC4GB tapes show a length on the label). Maybe *that* is why a V4R4 GO SAVE 21 to a QIC2DC tape failed on the V4R4 box.

I've always tried to avoid a situation like that: The need to change tapes in the middle of a save 21. I don't even know if you'll get a tiny "there's a message" symbol on your console, indicating "look at QSYSOPR messages" to read you should insert a new tape.

For "no mention of length", maybe do some internet research. That could be a challenge, since (according to Wikipedia) QIC has more possible formats than I expected, and a 2GB format isn't mentioned in that article, nor in the SLR article. However, QIC is a standard by itself and thus I expect there exists some documentation about that, with the parameters you need to actually know what fits (apart from using DC, because the compression ratio isn't fixed and highly depending on the data being compressed).

Anyway, if some event happens, I'd expect it to be mentioned in some job log. Everything else is just guessing.

:wq! PoC