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MainView for z/OS
MainView for z/OS
MainView for z/OS: All Versions
What are the Best Practices for limiting the CPU consumption of the MainView for z/OS Device views?
A view such as DEVSTAT displays every I/O device defined in the system. This could be a very large query set and could result in unnecessary overhead.
The following example provides some suggestions on how to limit the cpu consumption of the device views when evaluated frequently with MainView Alarm Manager, MainView Explorer or via Screens in ASU mode.
It is recommended to use the QWHERE and WHERE filtering mechanisms. These are used for data queries that pass through the MainView Infrastructure. Views and alarms use data queries to obtain the data that MainView monitoring products collect.
Use QWHERE DXGTYPC = 3390 to limit the query set to only 3390 devices and significantly reduce the amount of data to be processed by the display manager.
QWHERE retrieves data from a MainView product and filters the data before the data is returned to the requester (view, alarm or API call). Use QWHERE when a query is being driven repetitively (such as with MainView Alarm Management) and appropriate filters will reduce the overhead of delivering the data required to satisfy the requirement.
Once the results of the QWHERE are stored in memory, use WHERE to filter the stored data to display varying information without having to perform the query again.
For example, issuing the following WHERE commands would not refresh the data. The data would be pulled from the existing results, saving the overhead of requesting the data again each time.
WHERE DXGSER = PROD*
limits the display to 3390 devices having VOLSERs prefixed with PROD
WHERE DXGSER = DEVL*
limits the display to 3390 devices having VOLSERs prefixed with DEVL
For further information, please see the MainView User Guide, Chapter 6, Customizing views.
- MainView Infrastructure
- MainView for z/OS