Operator test procedures
After you have prepared procedures for operating IMS, all those who operate the system should be given an opportunity to familiarize themselves with the procedures. After that, all procedures should be thoroughly tested.
Simulating system failures
To test some of the recovery procedures, certain types of system failures must be simulated. The following table shows possible failures and how they can be simulated.
| System failure | Simulated by |
|---|---|
| BMP or CCTL thread abended or canceled in error | Use MTO command /STOP REGION n ABDUMP. |
| IMS control region abended or canceled in error | Use z/OS® MODIFY or CANCEL command. |
| MPP abended, looping, or in wait state | Use one of your own programs, or use the DL/I test program DFSDDLT0; use the special calls ABEND and ZING. |
| CCTL abended, looping, or in wait state | Use one of your own programs. |
| I/O error on SLDS or RLDS | Use an SLDS or RLDS that has previously been damaged. Reset, rewind, and reload tape drive. |
| z/OS error (loop or abend) | Unplug or switch off z/OS system residence drive. Cancel IMS control region. |
| Hardware error, no loss of real storage | Unplug or switch off z/OS system residence drive. |
| Power® failure, or hardware error with loss of real storage | Press System Reset, and re-IPL. |
Qualities of good tests
The specific nature of your IMS use and installation setup will determine the details of your testing program. However, all good tests have these qualities in common:
- They are realistic.
- They are specific—addressing each one of the many possible operating situations.
- They involve the same people who operate IMS in actual, production-mode situations.
- Their results are verifiable.
Improvement through feedback
Although formal testing of your procedures ends when production begins, each actual instance of operation and recovery can be considered a test—a chance to improve your procedures. If problems develop or procedures are found to be vague or inaccurate, you should use this experience to update and improve your procedures.
You might also want to consider conducting periodic reviews of your procedures by your operations staff and system administration staff. Such reviews are particularly important as you add maintenance to your IMS system or upgrade to a new release of IMS.
Retesting when the system changes
Any time you significantly change your system, you should do at least some retesting. Changes could be in the form of either a new release or major upgrade of IMS itself, or a redesign or expansion of your production setup.
The retesting should verify that your old procedures still function properly in the new environment.