Modify attributes of paging areas
Component: | BS2000 |
Functional area: | System control and optimization |
Domain: | SYSTEM-TUNING |
Privileges: | TSOS |
Routing code: | R |
Function
The MODIFY-PAGING-AREA-ATTRIBUTES command is used to modify the attributes of one or more paging areas.
Format
MODIFY-PAGING-AREA-ATTRIBUTES | ||||||||||||||||
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Operands
VOLUME = *ALL / *PUBSET(...) / list-poss(256): <vsn 1..6>
Specifies which paging files are to be changed.
VOLUME = *ALL
Changes the attributes of all used paging files on SF and SM pubsets of the system.
VOLUME = *PUBSET(...)
Specifies one or more SD pubsets. The attributes of the paging file are to be changed on each volume of the specified SF pubsets.
PUBSET = list-poss(256): <cat-id 1..4>
Specifies the SF pubsets via their catalog number.
VOLUME = <vsn 1..6>
Specifies the volume serial number (VSN) of the disk on which the paging file to be changed is located. Up to 256 disks can be specified.
UTILIZATION = *LOW / *MEDIUM / *HIGH
Specifies how a paging file is to be utilized. This affects both use of the paging file and the duration and I/O rate of a reduction of the paging files.
Paging management takes this specification into account as far as possible, but it cannot guarantee that a paging file will be utilized in the desired manner. This ultimately depends on the actual paging rate and on the behavior of the paging load over time.
UTILIZATION = *LOW
The paging file is to be utilized less intensively than envisaged in the paging strategy (the paging file will hold pages less frequently). This setting is particularly advisable if the paging file is intended to be removed from the paging area (paging file reduction) or if frequent DMS I/O is to be expected on the paging disk in addition to the paging I/O (typically applies to paging files in the home pubset).
UTILIZATION=*LOW applies to the paging files in the home pubset if they are added to the paging area at system startup. Paging files that are not on the home pubset and that are added to the paging area via the paging parameter service are covered by UTILIZATION=*MEDIUM.
UTILIZATION = *MEDIUM
The paging file is to be used in accordance with the paging strategy, which means that paging files will be utilized evenly in proportion with their size.
UTILIZATION = *HIGH
The paging file is to be utilized more intensively than envisaged in the paging strategy (the paging file will hold pages more frequently). This is typically helpful with small files, as it is a way to reduce the load on disks with large files, allowing the paging files to be utilized evenly, irrespective of size. It is also possible to cut the time required for the reduction of large paging files.
Notes
Before the attributes can be redefined, the paging file must already have been added to the paging area. The pubset of the paging file which is having its attributes redefined need not have been imported.
If a paging file which is being released is relatively heavily utilized, you must anticipate the command taking a long time to relocate the virtual pages to other paging files, heavy I/O traffic, and a high CPU load. To lessen these loads and to simplify the reduction process, it is advisable not to start reduction immediately, but first to minimize the paging utilization of the paging file in question (UTILIZATION operand, value *LOW). From then on the paging file in question will (as far as possible) no longer be used to hold virtual pages. Thereafter, through page access and release, the contents of the associated paging file will be diminished in size, with the result that less I/O is needed to swap the pages out in the actual reduction process. There is, however, a chance that it will not be possible to get by without swapping pages into the paging file because the paging rate is too high, or conversely that the pages in the paging file will not be accessed. In these cases the command will have no effect.
Whether modifying the paging utilization to *LOW will bring the hoped-for success can be determined with the SHOW-PAGING-CONFIGURATION command: If the free size of the paging area concerned increases, the modification was successful. The SHOW-PAGING-CONFIGURATION command also indicates the time when the actual reduction process is to start. This may be after a few minutes, but periods of an hour or more are also conceivable.
Return codes
(SC2) | SC1 | Maincode | Meaning/Guaranteed messages |
|---|---|---|---|
0 | CMD0001 | Command executed without error | |
32 | EMM2800 | The function cannot be continued because of an internal error | |
64 | EMM2804 | The paging area on the specified volume is not in use | |
64 | EMM2805 | The MRSCAT entry of the pubset is missing | |
128 | EMM2807 | The function cannot be continued due to a lack of resources |
Examples
The paging file on disk 2OSW.0 is to be utilized less intensively because reduction of the paging area is planned:
/MODIFY-PAGING-AREA-ATTRIBUTES VOLUME=2OSW.0, UTILIZATION=*LOW