IBM manual 26.3 VM, LPAR, or Standalone Systems, OS/390 Production Stand-By Maintenance

3Final System Test on OS/390

Just before you migrate to OS/390, you should run all your important applications in parallel, using the same environment as above. Compare the results of both systems to make certain there are as few surprises as possible.

4Final Production Cut-Over to OS/390 (²D² Day?)

When you finally migrate your production applications to OS/390, you will need a backup VSE system standing by for emergency rerun of applications that uncover any conversion problems after you go live.

￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿			￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿			￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿
￿	OS/390	￿	￿	VSE	￿	￿	OS/390	￿
￿	Production	￿	￿	Stand-By	￿	￿ Maintenance		￿
￿		￿	￿		￿	￿		￿
￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿			￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿			￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿

5After Production Cut-Over to OS/390

Once you are in production, you still need an on-going test system environment for applying maintenance, and testing new releases of OS/390 and subsystems.

Even after the migration is complete, you will still want to keep a backup

VSE system around for emergency, but this requirement will fade over time.

￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿			￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿			￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿
￿	OS/390	￿	￿	OS/390	￿	￿ VSE Backup	￿
￿	Production	￿	￿ Maintenance		￿	￿	￿
￿		￿	￿		￿	￿	￿
￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿			￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿			￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿

26.3 VM, LPAR, or Standalone Systems

Now that we have sketched briefly the number and types of operating system images that will be involved in this migration, we need to consider a very important question. What is the best way to implement these multiple system images for the migration period, and perhaps into the future given the need for test and backup OS/390 systems? When considering implementation of multiple system images the following set of choices exist:

∙Separate hardware platform for each system image (included here would be consideration of using P/390s to support single system images)

∙

∙

∙

∙

Physical partitioning of a single or multiple hardware platforms

Logical partitioning of a single or multiple hardware platforms

Software partitioning of a single or multiple hardware platforms

Some combination of the above choices

The choice you make from the above set depends on many variables such as: your current hardware environment, the hardware environment you may be migrating to, your current and future software environment, the physical space you have available for hardware, your hardware and software budget, the skill set of your I/T staff, and so on. Each of the choices listed above has positive and negative aspects depending upon how your environment maps to the variables described. It would be possible to enter into a lengthy discussion of how to

Chapter 26. Test Environments 421