This workspace provides information about the use of your z/OS system's real storage in terms of various types of frame counts, slot counts, and paging rates.
Note: This workspace still includes expanded storage in the views, but the value for this data will always be 0 for supported z/OS system versions, which no longer support expanded storage.
The real storage manager (RSM) is the z/OS component responsible for the use of central and expanded. The Real Storage table view provides information about the factors affecting performance as it relates to real storage.
The first bar chart in the workspace illustrates the unreferenced interval count. The unreferenced interval count is inversely related to contention for real storage. The lower the unreferenced interval count, the more quickly frames are being referenced. In some cases, a low count is not necessarily indicative of a paging problem. To determine whether real storage is being overused, use this factor in conjunction with the page fault rate displayed in the System Paging Activity workspace.
The second bar chart illustrates available frames. This chart gives you a sense of how much uncommitted storage is available for use.
Note: The following two charts display no data in the current release.
The third bar chart illustrates the migration rate. The expanded storage migration rate is the number of pages per second being moved from expanded to auxiliary storage. Triggered when the age of expanded storage frames falls below a certain level, a high migration rate may indicate that the expanded storage is being depleted. This may cause increased z/OS overhead and erratic performance as referenced pages are brought in from slower auxiliary storage. Because this value applies to migration from expanded to auxiliary storage, the value for the central storage bar should be 0.
The fourth bar chart illustrates the number of pages written to or read from expanded storage. Pages written to expanded storage are written from central storage by the SRM to relieve real storage contention. Because these pages can be moved quickly between central and expanded storage, a high page rate may not be a problem. It may, however, contribute to increased overhead as well as depletion of expanded storage, which can cause performance problems as pages are migrated from expanded to auxiliary storage.
Pages read from expanded storage are read to central storage as a result of a swap-in or page fault. Between central and expanded storage, a high page rate may not be a problem. It may, however, contribute to increased z/OS overhead.
This workspace can record history.
See also:
Organization
of system-level predefined workspaces
Attribute groups used by system-level predefined workspaces