IBM OS/390 User Manual
separate operating systems, or the division of tape files and tape volumes
between two tape managers running on two separate operating systems.
between two tape managers running on two separate operating systems.
3.3.7 Standardized Conversion Deliverables and Automation
A significant objective for today
′
s VSE or OS/390 mainframe installation is the
standardization of their application components (JCL streams, application code
and data files), associated naming conventions and operation procedures. The
standardization of conversion deliverables is directly related to the degree of
automation used to perform the conversion. The more automation is used, the
more standardized the deliverables will be. Mass conversions are typically more
automated than progressive conversions.
and data files), associated naming conventions and operation procedures. The
standardization of conversion deliverables is directly related to the degree of
automation used to perform the conversion. The more automation is used, the
more standardized the deliverables will be. Mass conversions are typically more
automated than progressive conversions.
It is also much easier to guarantee complete and consistent compliance with
standards and naming conventions when the entire inventory is converted and
switched from VSE to OS/390 over a single weekend using a single automated
conversion process, as in the mass conversion approach. Contrarily, it is difficult
to guarantee a good compliance with standards and naming conventions when
the conversion of application kernels spans over many months and may be
assigned to separate conversion teams, as in a progressive conversion. The
same conversion requirement may be addressed differently by different people
at different times.
standards and naming conventions when the entire inventory is converted and
switched from VSE to OS/390 over a single weekend using a single automated
conversion process, as in the mass conversion approach. Contrarily, it is difficult
to guarantee a good compliance with standards and naming conventions when
the conversion of application kernels spans over many months and may be
assigned to separate conversion teams, as in a progressive conversion. The
same conversion requirement may be addressed differently by different people
at different times.
3.3.8 Risk Management
The comparative risk of both conversion approaches has changed over the
years.
years.
The risk of disrupting your production system, when dividing it into dual
operating environments, has increased in proportion with the VSE application
portfolios increase in size, complexity and integration.
operating environments, has increased in proportion with the VSE application
portfolios increase in size, complexity and integration.
With mass conversions, the regimen of performing multiple successful rehearsal
conversions has refined the mass conversion approach and its single switchover
weekend into a mature and predictable, therefore safer solution.
conversions has refined the mass conversion approach and its single switchover
weekend into a mature and predictable, therefore safer solution.
It is today safer to use the mass conversion approach than the progressive one
for large application portfolio, and in some cases of high integration, there is
simply no other way.
for large application portfolio, and in some cases of high integration, there is
simply no other way.
3.3.9 Complexity of Implementation
Still, the mass conversion approach requires more skills and experience than
the progressive conversion approach.
the progressive conversion approach.
The conversion of one single application kernel requires less integrated
automation, therefore less complex (and less expensive) conversion tools. Due
to the reduced size of a kernel, it is fairly easy to recover manually from
automated conversion defects. The migration of a single kernel requires less
planning than the conversion of the entire portfolio. Consequently, the
progressive conversion approach has an easier learning curve, which makes it
easier to implement with internal non-conversion-expert staff only. They learn
while they do it.
automation, therefore less complex (and less expensive) conversion tools. Due
to the reduced size of a kernel, it is fairly easy to recover manually from
automated conversion defects. The migration of a single kernel requires less
planning than the conversion of the entire portfolio. Consequently, the
progressive conversion approach has an easier learning curve, which makes it
easier to implement with internal non-conversion-expert staff only. They learn
while they do it.
Contrarily, the mass conversion approach requires highly integrated automation,
therefore complex and expensive conversion tools. Due to the size of the
conversion inventory, it is difficult or impossible to recover manually from
therefore complex and expensive conversion tools. Due to the size of the
conversion inventory, it is difficult or impossible to recover manually from
Chapter 3. Developing the Plan
51