I was looking at a couple of documents describing the Pertec tape interface;
the manual for my Kennedy 9610 tape drive, and a nice reference by a fellow
with a rather familiar name:
http://www.sydex.com/pertec.html
According to my Kennedy manual, issuing a read command causes the drive to
return one block of data. I can see how that would be used in block-oriented
applications in which blocks may be randomly read, written and re-written on
the tape. But most of my magtape experience has been using the tapes in a
streaming mode, such as when reading/writing one or more tar archives separated
by file marks.
When writing a tar archive on a magtape from a Unix system, is the archive
written as a sequence of fixed-size blocks? Or is the entire tar archive
effectively written as one continuous block which must be streamed with no
repositioning?
I'm curious because I'm daydreaming about how to build a tape drive interface
controller, and I wonder whether it might need to potentially stream an entire
tape in one go vs. being able to safely assume some maximal block size.
--
Mark J. Blair, NF6X <[email protected]>
http://www.nf6x.net/
