Change Journal Attributes (CHGJRNA)
| Where allowed to run: All environments (*ALL) Threadsafe: Yes |
Parameters Examples Error messages |
The Change Journal Attributes (CHGJRNA) command is used to change system wide attributes for all journal environments on the system.
When a system wide journal attribute is changed, the changed attribute will go into effect immediately for all applicable journal environments on the system. Not every journal environment will be affected by a change to a system wide journal attribute. For example, if caching is not enabled for a local journal then the cache wait time will have no affect on that journal environment. Also, if the journal recovery count for a local journal is not set to *SYSDFT then the system wide journal recovery count will have no effect on that journal environment.
Restrictions:
- You must have job control (*JOBCTL) special authority to change the JRNRCYCNT or CACHEWAIT parameters.
- This command is shipped with public *EXCLUDE authority, and the QPGMR and QSYSOPR user profiles have private authorities to use this command.
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Parameters
| Keyword | Description | Choices | Notes |
|---|---|---|---|
| JRNRCYCNT | Journal recovery count | 10000-2000000000, *SAME, *SYSDFT | Optional |
| CACHEWAIT | Cache wait time | 1-600, *SAME, *SYSDFT | Optional |
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Journal recovery count (JRNRCYCNT)
Specifies the system default journal recovery count. The journal recovery count allows you to choose between faster runtime processing of changes to journaled objects and faster IPL or vary on recovery after an abnormal shutdown. The value specified influences the frequency with which journaled objects are forced to auxiliary storage as those objects are changed. The specified journal recovery count indicates the approximate number of journaled changes that would need to be recovered during journal synchronization for this journal in the event of an IPL or vary on after an abnormal shutdown. Specifying a smaller value decreases the number of changes that would need to be recovered from this journal by increasing the frequency with which changed objects are forced to disk. Specifying a larger value increases the runtime processing of changes to journaled objects by decreasing the frequency with which changed objects are forced to disk. Changing this value may affect overall system performance as it affects the utilization of auxiliary storage devices.
Note: This parameter changes the system default journal recovery count for all newly created journals on the system and all existing journals that have the system default (*SYSDFT) specified for their journal recovery count. To set the journal recovery count of a specific journal to a value other than the system default, please refer to the Journal recovery count (JRNRCYCNT) parameter on the Change Journal (CHGJRN) command.
- *SAME
- This value does not change.
- *SYSDFT
- The system wide journal recovery count is set to the default value of 250,000.
- 10000-2000000000
- Specify the system wide journal recovery count.
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Cache wait time (CACHEWAIT)
Specifies the cache wait time for journal environments with caching enabled. The cache wait time is the maximum number of seconds that the system will wait before writing any lingering journal entries from main memory to disk.
When a journal environment has journal caching enabled, the system stores journal entries in main memory until the sum of all the journal entries equals the maximum amount of data that can be written in one disk write. Then all the journal entries are written to disk together. This allows for optimum journal performance when the journal is busy. However, if the journal is not busy, the system will wait for the entries in main memory to accumulate until they equal the maximum size of one disk write. This parameter guarantees that the system will wait no longer than the specified number of seconds before writing any journal entries lingering in main memory to disk.
Note: This parameter only applies to journals that have caching enabled. To enable or disable journal caching, please refer to the Journal caching (JRNCACHE) parameter on the Create Journal (CRTJRN) or Change Journal (CHGJRN) command.
- *SAME
- This value does not change.
- *SYSDFT
- The cache wait time is set to the system default of 30 seconds.
- 1-600
- Specify the cache wait time in seconds.
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Examples
Example 1: Changing the System Wide Journal Recovery Count
CHGJRNA JRNRCYCNT(500000)
This command changes the system wide journal recovery count to 500,000.
Example 2: Changing the System Wide Cache Wait Time
CHGJRNA CACHEWAIT(60)
This command changes the system wide cache wait time to 60 seconds.
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Error messages
*ESCAPE Messages
- CPF90FF
- *JOBCTL special authority required to do requested operation.
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