[evlatests] lando replacement

[Bill Sahr]

The replacement of the database server named lando by the server
currently known as lando-new has been rescheduled for the double
maintenance days that fall on Tue, 11/12 & Wed, 11/13.

With this change the names "lando-new" and "lando-new.evla.nrao.edu"
will disappear from our network.  Any/all programs, scripts, etc that
reference these names must be changed.  Details on how best to make
the change are given at the end of this posting.

During the changeover, both lando & lando-new and all of the databases
on these two systems will be unavailable.  The affected databases are:
     - evlaparm, the EVLA parameters dbase,
     - evlampts, the main database for EVLA monitor data,
     - widarmpts, the main database for widar correlator monitor data

There are standby versions for all of these databases.  There is a
standby version of evlaparm on r2d2.  Monstdby on r2d2 is the standby
dbase for EVLA monitor data, and widarmpts on mcsql is the standby
for widar correlator monitor data.

While special steps must be taken to make evlaparm on r2d2 the
operational version of the parameters dbase, monstdby on r2d2 and
widarmpts on mcsql can be accessed via the monitor data query interface
simply by selecting them from the dropdown database menu located in
the upper right hand corner of the interface web page.


Eliminating the name "lando-new"
Changing the name "lando-new" to "lando" is definitely not the best way
to adapt programs or scripts  to this change.  There is no guarantee
that the name "lando" will continue to be used.  However, there are
aliases, in the form of CNAMEs, that are guaranteed to continue to be
used and to remain unchanged.  The aliases are based on the names of
the databases.

The available aliases are:

evlaparm-proddb.evla.nrao.edu
Will always point to the system currently hosting the production
version of the evla parameters dbase.

evlampts-proddb.evla.nrao.edu
evlampt-proddb.evla.nrao.edu
Will always point to the system hosting the production version of
the evla monitor data archive.  "evlampts" is to be preferred over
"evlampt".

widarmpts-proddb.evla.nrao.edu
Will always point to the system hosting the production version of
the widar correlator monitor data archive.

Even if the production version of one of these database goes down
or is taken offline, the CNAME will be altered, at the router level,
to point to the standby database, thereby offering continued access
to the data with no changes needed in the script or application.

If you have any questions or wish to raise any issues, please contact
either me, Bill Sahr, or Daniel Lyons.

Thank you.