bug report etiquette

[Jeff Siegal]

In article <3261 at bloom-beacon.MIT.EDU> nessus at athena.mit.edu (Doug Alan) writes:
>The TK50 performs very very very slow and unreliably if it
>doesn't get to stream.  The block device is double buffered, while the
>raw device is not.  If the raw device is used [...], the
>tape drive doesn't stream.  If the block device is used [...],
>the tape drive does stream, [...].

In addition to the buffering, the block device forces an abysmally
small block size (as Chris pointed out).  This is a conventional way
to make streaming tape drives stream (by reducing the tape data rate
and density), and also a great way to cripple a tape subsystem.  A
much better way to drive such devices is with raw, asynchronous I/O.
Oh, Unix doesn't do that?  Hmm, I thought there was this other
operating system for VAX's, but I can't seem to remember the name
right now... 

Jeff Siegal