Exabyte tape drives: responses and a warning.

[Ray Butterworth]

It seems that most of our random problems were caused by noise from
a cable that wasn't properly shielded and grounded.

The controller boards are produced by different companies,
and so not all Exabytes will behave the same way.

Thanks to all the people that responded to my question.

Nearly all the responses indicated that they were happy with the drives.

The only complaints were about the slow response time for changing
tape motion (e.g. backspace, rewind), and that it is impossible
to see the tape itself to visually determine where it is and what
it is doing.  This latter feature is definitely very frustrating.

A word of warning to UNIX users though:

One of the simple tests I tried was
    cat /etc/termcap >$TAPE
    cat $TAPE >/tmp/termcap
    diff /etc/termcap /tmp/termcap
and both cat's exited successfully, even though the diff showed
differences in the files.

Like most UNIX software, cat doesn't check the return status of
close() or fclose(), so if anything goes wrong during the close
of the file the error is silently ignored.

These devices use a very large buffer, and in many cases
the tapes don't even start to move until the write-end-of-file
command is issued by the device driver in the close.  If anything
goes wrong and the data isn't written correctly, the close()
function returns an error status but everything simply ignores it.

If you are writing (or buying) software that is going to write
to these devices, I strongly suggest you make sure that it
checks the return value of close().