[JR@YUKON.SCRC.Symbolics.COM: Incremental tape re-use]

[Paul Pangaro <pan%athena.pangaro.dialnet.symbolics.com@RELAY.CS.NET>]

 (The following unedited transcript of a first draft converstion.)

    Date: Wed, 9 Aug 89 15:55 PDT
    From: Richard Lamson <rsl@MAX-FLEISCHER.ILA-SF.Dialnet.Symbolics.COM>

Thank you Richard for the most intelligent comments on the net lately
(considering also my own).

    Automating corporate memory is quite difficult without adequate tools,
    as you probably know, Paul.

I know a man who, lacking 128 bytes, made it out of a 4-lb piece of
metal that had pins in it (wired into a configuration), which when
screwed into a larger, 40-lb box taking the place of a microcomputer,
provided the 128 bytes as a data read. This was 1955. What tools who?

                  I was part of Symbolics' Software Support
    during at least three separate design efforts, none of which was
    satisfactory. 

This means that it is hard, not that you did a good job.

          This is made incredibly more difficult by the fact that
    Symbolics is a bicoastal company.

No, this merely makes it more important that it be done.

    Part of the problem is that "Corporate Memory" is a distinctly
    associative memory, and the potential number of elements in the domain
    of the relation is quite large.  Even in the limited amount of corporate
    memory that Symbolics passes out to the world, it is not always possible
    to determine if the information you want is available: try discerning
    from the documentation whether it is possible to append to cartridge
    tapes, for example, and you will find nothing but this one tantalizing
    reference:

	   Tape when done    This controls what the dumper does with the tape
			     when it has finished passing over all the specified
			     pathnames. These are the available options:
    [...]
			     Leave            Leaves the tape positioned at
					      the end without rewinding it or
					      putting it offline. It declares the
					      dump finished. It facilitates more
					      dumping later, by leaving the
					      tape in the correct position for
					      using "Append to tape" in a later
					      dump invocation.

    The "Append to tape" option itself is not documented.  Of course, the
    documentation itself appears to have been produced by a writer who was
    using the backup system to dump to a cartridge, so they didn't even see
    the "Append to tape" question to document it (that question is
    suppressed if you are dumping to cart).  Note the figure in that
    documentation section.

    By the way, the answer to the original question about appending to
    cartridges is that while appending is not possible, it IS possible to
    cause the dumper to re-dump those files which were on the original tape
    in limited circumstances.  I recommend that people to consolidated dumps
    back to a date certain rather than incremental dumps, at least some of
    the time.  For example, I do complete dumps approximately twice a year,
    consolidated dumps back to the most recent complete (or sometimes to a
    convenient consolidated, if a lot has changed) weekly, and incremental
    tapes (approximately) daily.



(I am not up to commenting at the above, it is too beautiful to tamper
with, and too much like fire that it will burn my typing tips.)


Best,
PANgaro