Extend paging area
Component: | BS2000 |
Functional area: | System control and optimization |
Domain: | SYSTEM-MANAGEMENT |
Privileges: | TSOS |
Routing code: | R |
Function
The EXTEND-PAGING AREA command enables systems support to extend the paging area to a maximum size of 4 Tbytes by adding one or more paging files (paging areas).
A paging file is either specified directly via the volume on which it is located or via the catalog ID of the pubset to which the volume belongs. The specification via pubset is only possible for SF pubsets. The specification refers to all paging files on the volumes of the respective SF pubset.
Format
EXTEND-PAGING-AREA | ||||||||||||||||||||
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Operands
VOLUME = *ALL / *PUBSET(...) / list-poss(256): <vsn 1..6>
Specifies the paging files to be attached.
VOLUME = *ALL
All unused paging files that belong to the imported, exclusively occupied pubsets are attached.
VOLUME = *PUBSET(...)
Specifies one or more SF pubsets. All paging files on the volumes of the specified SF pubsets are attached.
PUBSET = list-poss(256): <cat-id 1..4>
Specifies the SF pubsets via their catalog ID.
VOLUME = list-poss(256): <vsn 1..6>
Specifies the volume serial number (VSN) of the disk on which the paging file being added is located. Up to 256 disks can be specified.
UTILIZATION = *MEDIUM / *HIGH / *LOW
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 = *MEDIUM
This default setting should be changed only in exceptional circumstances.
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
This setting should be selected only in exceptional circumstances.
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 paging 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.
UTILIZATION = *LOW
This setting should be selected only in exceptional circumstances.
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 (reduction) or if frequent DMS I/O is to be expected on a paging disk in addition to the paging I/O (primarily 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.
LATER-REDUCTION = *NOT-REQUESTED / *REQUESTED
This operand specifies how likely it is that the paging area will subsequently be reduced by removal of the paging files. This specification is evaluated when the paging files attached by this command are detached.
LATER-REDUCTION = *NOT-REQUESTED
This default setting should be changed only in exceptional circumstances.
Subsequent reduction of the paging area by removal of the paging files is not intended. If reduction is carried out nonetheless, the acceleration mechanism will not be used (no additional resources will be requested).
LATER-REDUCTION = *REQUESTED
This setting should be selected only in exceptional circumstances.
It is possible that the paging area will later be reduced by removal of the paging files attached by this command.
When assigning this operand value you should bear in mind that main memory utilization will be greater the whole time that the paging file is in the paging area if later reduction of the paging area is envisaged (performance accelerated by requesting additional resources) and that this is very likely to result in a higher paging rate, which in turn may have a negative impact on the overall performance of the system. Consequently, it is possible that extension of the paging area will have to be rejected. So *REQUESTED should be used with caution.
Return codes
(SC2) | SC1 | Maincode | Meaning/Guaranteed messages |
|---|---|---|---|
0 | CMD0001 | Command executed successfully | |
1 | CMD0001 | The paging area on the specified magnetic disk is already in use | |
32 | EMM2800 | The function cannot be executed because of an internal error. | |
64 | EMM2802 | The specified magnetic disk is unknown, the paging file does not have the required file attributes or the paging file is larger than 2048 GB...... | |
64 | EMM2803 | The pubset is a shared pubset. | |
64 | EMM2804 | There is no paging file on the volume or pubset | |
64 | EMM2805 | The pubset has not been imported, the SM pubset has not been imported completely, the pubset's MRSCAT entry is missing, the disk cannot be occupied, a disk error occurred or the paging file cannot be processed because of an input/output error | |
64 | EMM2806 | The paging file specified means that the size of the paging area exceeds the 4 TB limit or the maximum permitted number of 4096 paging files has been reached | |
128 | EMM2807 | The function cannot be executed because of a lack of resources |
Notes
Message EMM2301 is issued for each paging file added. On completion of command processing, message EMM2850 is issued. This message indicates the current availability of paging space and the current paging space requirements.
The pubset to which the disk containing the paging file belongs must have been imported. It may not be a shared pubset.
The disk from which the paging file is taken may also be a DRV (Dual Recording by Volume) disk, but in this case, the pages will be written just once to one of the two DRV disks.
Example
Adding the paging file on the disk with the volume serial number 2OSW.0 to the paging area:
/EXTEND-PAGING-AREA VOLUME=2OSW.0