IBM OS/390 User Manual
5. Security
6. Performance
7. Capacity Planning
8. Testing
9. Backup/Recovery
10. Disaster Planning
11. Project Plan Development
6. Performance
7. Capacity Planning
8. Testing
9. Backup/Recovery
10. Disaster Planning
11. Project Plan Development
2.5 Approaches to Migration
2.5.1 Disclaimer
For the purpose of providing a more effective guide the mass migration method
was adopted as an approach or strategy in migrating. The reasons for the
choice are numerous, but they include:
was adopted as an approach or strategy in migrating. The reasons for the
choice are numerous, but they include:
•
Mass migration provides a project duration that is definable. This allows for
a more accurate migration project cost estimation and sizing.
a more accurate migration project cost estimation and sizing.
•
In today
′
s integrated I/T environments it is more difficult to define discrete
kernels. For example, many applications currently have integrated facilities
that support the integrated nature of many business functions. This can be
found in applications such as Enterprise Resource Planning (ERP). The sales
forecasting function, for example, shares information with certain accounting
functions. This makes it difficult to separate or define discrete kernels to
migrate.
that support the integrated nature of many business functions. This can be
found in applications such as Enterprise Resource Planning (ERP). The sales
forecasting function, for example, shares information with certain accounting
functions. This makes it difficult to separate or define discrete kernels to
migrate.
2.5.2 OS/390 Conversion and Production Implementation Strategies
There are two different strategies (or approaches) you can use in migrating
applications to OS/390. They are: (1.) the kernel/progressive approach, and (2.)
the single switchover - mass application migration approach. The decision as to
which approach to take will have a definite impact on the project, particularly on
the manner in which resources are deployed Additionally, the approach decision
will, in most cases, have the greatest impact on sizing the project. The following
discussion presents these two approaches.
applications to OS/390. They are: (1.) the kernel/progressive approach, and (2.)
the single switchover - mass application migration approach. The decision as to
which approach to take will have a definite impact on the project, particularly on
the manner in which resources are deployed Additionally, the approach decision
will, in most cases, have the greatest impact on sizing the project. The following
discussion presents these two approaches.
2.5.2.1 Kernel/Progressive Approach
Here, an installation defines discrete application sets called kernels
2
. The
conversion team uses progressive conversions of each defined kernel, placing a
converted kernel into OS/390 production on a
converted kernel into OS/390 production on a
″
when ready,
″
serial basis. After a
kernel is cutover
3
to OS/390 production, the next defined kernel is worked on,
converted, and implemented on OS/390. This process goes on until all
applications (kernels) are cutover to the OS/390 environment. Some points to
make about the
applications (kernels) are cutover to the OS/390 environment. Some points to
make about the
″
kernel approach
″:
2
A kernel is usually defined as all the programs and files that are needed to support a business application; for example, the
payroll system.
payroll system.
3
″
Cutover
″
is a term generally associated with the kernel approach. It is a word used to describe the completed conversion of
a kernel to OS/390; that is, the time when the kernel is placed in OS/390 production.
Chapter 2. Sizing the Effort
27