write(2) to tape with odd byte count

[Doug Gwyn <gwyn>]

Oh, boy!  Magtape driver wars!

> Oh, you're talking about the System V VAX TU78 driver maybe?  It
> doesn't give you the error return, it quitely pads to the nearest
> "word" so your copy tape isn't really a duplicate of the original.

I don't have any experience with this driver but that's a bug.

> The 4.2BSD TU78 driver works with any byte count <= 63k.  The 4.3BSD
> driver will also do "read-reverse" error correction for soft tape
> errors, recognize end of tape (finally), report hardware failures in
> human readable form and survive controller power failures without
> crashing the system or hanging the tape drives (except on 11/750,
> which gets "panic: cbhung" after a while).

I hope they fix the driver so it moves to the next tape mark when
closed in non-rewind mode.  It's great fun to get the tail of a
file overwritten because of this misdesign feature.