IBM OS/390 User Manual
26.3.3.5 OS/390 Guest Considerations
The considerations for defining OS/390 guests are no different from those
associated with defining VSE guests. From the VM/ESA point of view, the actions
taken to maximize the performance of a VSE guest, would be the same as those
taken to maximize an OS/390 guest. For example, specifying resource goals is
done through the SHARE directory statement. Best performance is achieved by
making the guest a preferred guest (V=R, or V=F), along with dedicating as
many devices as possible. Other VM level scheduler controls such as setting
STORBUF, or the DSPSLICE would be modified in a similar manner for both VSE
and OS/390, since from the VM point of view both are virtual machines with long
running units of work.
associated with defining VSE guests. From the VM/ESA point of view, the actions
taken to maximize the performance of a VSE guest, would be the same as those
taken to maximize an OS/390 guest. For example, specifying resource goals is
done through the SHARE directory statement. Best performance is achieved by
making the guest a preferred guest (V=R, or V=F), along with dedicating as
many devices as possible. Other VM level scheduler controls such as setting
STORBUF, or the DSPSLICE would be modified in a similar manner for both VSE
and OS/390, since from the VM point of view both are virtual machines with long
running units of work.
26.3.4 Summary
In summary, use of VM/ESA as a migration tool will enable you to focus more on
the migration tasks, and less on tasks associated with creating a migration
environment. Since this document is concerned with migrating from VSE to
OS/390, we will now turn to more specifics concerning that task.
the migration tasks, and less on tasks associated with creating a migration
environment. Since this document is concerned with migrating from VSE to
OS/390, we will now turn to more specifics concerning that task.
26.4 Parallel Activities
Throughout the above stages of migration, there will be many activities
overlapping with one another, not the least of which are your daily production
computing workload and conversion activities. The following considerations
should also be factored into your choice and design of test system, including
their configuration, availability and performance characteristics.
overlapping with one another, not the least of which are your daily production
computing workload and conversion activities. The following considerations
should also be factored into your choice and design of test system, including
their configuration, availability and performance characteristics.
26.4.1.1 Overlapped Activities
The number of
″
test
″
OS/390 systems will determine what can be done
simultaneously by different people, or by the same people without having to
restore volumes or re-IPL.
restore volumes or re-IPL.
For example, you can schedule times for the maintenance system to be used
alternately by systems programmers for applying and testing maintenance, for
operator training, and for testing different operating system configurations or
options.
alternately by systems programmers for applying and testing maintenance, for
operator training, and for testing different operating system configurations or
options.
26.4.2 Synchronizing VSE Applications with OS/390 Versions
After you convert your applications to OS/390, you cannot freeze them on VSE.
Any changes to the programs, JCL, data, and operating procedures in the VSE
production environment must be replicated to OS/390. You need to schedule a
replication or re-conversion of these applications to the OS/390 libraries after
they are converted.
Any changes to the programs, JCL, data, and operating procedures in the VSE
production environment must be replicated to OS/390. You need to schedule a
replication or re-conversion of these applications to the OS/390 libraries after
they are converted.
26.5 Building the Initial OS/390 Test System
Once you turn your initial OS/390 system over to application programmers for
the real conversion activities, you need to create a second OS/390 system for
testing. As part of this, you should give careful consideration to what is shared
between the two OS/390 systems, and how isolated they are.
the real conversion activities, you need to create a second OS/390 system for
testing. As part of this, you should give careful consideration to what is shared
between the two OS/390 systems, and how isolated they are.
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VSE to OS/390 Migration Workbook