SCSI tape question

[Chuck Guzis]

On 12/12/2014 09:04 PM, Jon Elson wrote:

> OK, that narrows things down QUITE a bit.  I worked with some Exabyte
> drives and others that had a lot of constraints on what you could do,
> and you could do some interesting things.  I think you could write
> zero-length blocks, and they would show up just like that when
> read.  Clearly on 9-track, there SHOULD BE no such thing as a
> zero-length block, but I suppose some drives could actually write
> such a thing at 1600.  A preamble, CRC, LRCC and postamble, with
> no data.  But, that OUGHT to be an illegal command.

I seem to remember on certain tapes, that very short records are 
discarded or reading;  something like a "noise" threshold of 7 bytes. 
But that could be for 7-track and 800 9-track.  I don't recall--but 
regardless, mistaking a 0-length record, should one occur, for a 
filemark is not catastrophic.

--Chuck