[evlatests] Old Monitor Data, Important Addendum

[Bill Sahr]

The old EVLA Monitor Data Archive has been in existence
since approximately November or December of 2003.  So,
my proposal that we do not attempt to maintain access
to this data once the new monitor data archive has been
operational for a few months means the loss (in effect)
of some 2 1/2 years of EVLA monitor data plus whatever
VLA monitor data has found its way into the EVLA monitor
data archive over that time period.

Now, please consider this point.  When we turn off the
Modcomps, all VLA monitor data will, in effect, be lost.
Yes, the tapes containing the VLA monitor data will still
exist.  However, all of the software that knows how to
reads these tapes, restore the data to disk in the expected
format, and to search through that data once it has been
restored to disk is all Modcomp based.

So, the question of what to do with old monitor data
becomes two-fold.  First, do we preserve the EVLA monitor
data that has been archived upto now?  Does "preserve"
simply mean that we archive the data, or does it mean
that we also do what is needed to guarantee that the
data is accessible?  Is it meaningful to archive it
without making it accessible?

Second, do we preserve the old VLA monitor data.  And, again,
do we make it accessible?  Please be aware that the archival
copies of VLA monitor data are on 9-track tape.  If this
data is to be preserved in the strong sense of the word,
then a major effort must be undertaken first to move this
data onto some other media, and to then create software that
can read it, write it to disk in some sensible format, and
search it.  This effort would involve multiple man-years of
effort and the total cost that would be in the 100s of
thousands of dollars.

So, do we preserve old EVLA monitor data?  Do we preserve old
VLA monitor data?  How strongly do we interpret the word
preserve?  Is it enough that it is archived?  What if the
archival copies exist on media that will soon be unreadable?
Is archiving without accessibility worth doing?

Thank you.
Bill