28 Nov
2019
28 Nov
'19
2:56 a.m.
On 11/27/2019 2:31 PM, John Foust wrote:
I couldn't get any of the DDS-2 to read, either
on the original hardware that wrote them, or on a newer STD28000N drive I bought on eBay,
a pull from an old Apple server. I could write new tapes on the drive, just couldn't
read any old ones. My attempts included reading some tapes I know I'd received from
other people (that is, written on other drives) that I know I had been able to read on
this hardware back in the day. They wouldn't read, either.
That sounds like a
block size issue. Usually telling dd to use a larger
block than the tape has is fine, but if the default is smaller than
what's on the tape, it'll fail.
Depending on the drive firmware, the OS support for that particular
drive, etc, you may or may not get warnings or errors that actually mean
anything.
A long time ago, I attempted to read some 9-track TOPS-10 tapes using a
Sun and a 6250 BPI capable tape drive. Nothing would read, it looked
like there were actually no files on the tape whatsoever. So I gave up,
but kept the tapes because they contained a lot of personal stuff I had
done in high school and a few years after.
Years later, I got my hands on a Sun3/280 with 9-track tape drive, and
attempted to read them again. Same thing, looked like there were no
files on the tape. Started increasing the block size, and VOILA, got data.
Very odd circumstance, but block size has a lot to do with trying to
read tapes. QIC-150, 8mm, 9-track, I've run into it a lot.
art k.