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32.6.1.1 Converting the Development Material
This is the code that the systems programmers are working on. It is
recommended that the conversion of these materials take place as early as
possible. This conversion is not normally done at switchover time. It is not
production material.
This task generally coincides with the transfer of a significant number of
application developers to the OS/390 platform. Development under CMS or VSE
can continue to a point. Convert the work in progress and then move the people
to OS/390. This can occur three months before switchover all at once or be
moved in a staged approach each week. How these are moved depends on the
amount of development activity in progress, what stage of development it is in,
how much growth is happening and what machine resources are available.
Converting these materials and personnel to OS/390 before switchover also
provides extra experience in the environment.
32.6.2 Phase 6: Actual Conversion and Switchover
The actual conversion is the final mass conversion, starting with a final fresh
supply of the entire conversion inventory. Both actual conversion and switchover
are performed within two to four weeks, with the actual conversion starting on a
Monday, and the switchover being completed on a Sunday. Production testing is
used to validate the actual conversion before switchover. A final supply of
conversion inventory, a few days before switchover, is used to identify any late
VSE change control and to carry it over to the converted OS/390 application.
As opposed to trial conversions, the actual conversion is followed by a mass
migration of all permanent VSE production data files and databases to OS/390,
which requires a short production outage during the weekend (typically on early
Saturday morning). After the file migration, some (mostly weekend) jobs are
executed and some online applications are started and verified in actual
production mode.
During the month preceding the switchover, all parties participate in planning
and preparation activities. These activities produce the final file and database
migration JCL streams and switchover task lists.
The actual conversion and switchover are complete when the scheduled
production jobs and online applications have run successfully in the OS/390
environment.
The key elements of preparing for the actual conversion are:
•
Final JCL Conversion
•
Final Program Conversion
32.6.2.1 Final JCL Conversion
A key task associated with the final JCL conversion is freezing the production
database. The actual JCL conversion should be done as late as possible before
the switchover, but before the final program conversion.
Another key task is performing the known manual changes to the production
database. At this point, the production database is established in a final form, so
further modifications made to jobsets during VSE production must also be made
to the conversion tool production database. Implement a change control
516 VSE to OS/390 Migration Workbook