skip book previous and next navigation links
go up to top of book: HP OpenVMS System Manager's Manual, Volume 2:... HP OpenVMS System Manager's Manual, Volume 2:...
go to beginning of chapter: Managing Page, Swap, and Dump Files Managing Page, Swap, and Dump Files
go to previous page: Understanding Dump Files Understanding Dump Files
go to next page: Displaying Information About Page and Swap FilesDisplaying Information About Page and Swap Files
end of book navigation links

Understanding Page and Swap Files  



As part of memory management, the operating system makes efficient use of physical memory by moving information between physical memory and files stored on disk. The system does this in two ways: paging and swapping. Paging and Swapping Terminology defines these and related terms.

Table 2   Paging and Swapping Terminology
Term Definition
Paging
A memory management operation that provides the efficient use of physical memory allotted to a process. Paging moves infrequently used portions of a process workspace out of physical memory to a file. For more information about paging, refer to the OpenVMS Performance Management manual.
Page file
The file to which the system writes paged portions of memory. The OpenVMS installation process creates a page file named SYS$SYSTEM:PAGEFILE.SYS. If necessary, you can use SYS$SYSTEM:PAGEFILE.SYS in place of the system crash dump file. For more information, see Using the Page File to Store System Crash Dumps.
Swapping
A memory management operation that provides the efficient use of physical memory available for the entire system. Swapping moves the entire workspace of a less active process out of physical memory to a file. For more information about swapping, refer to the OpenVMS Performance Management manual.
Swap file
The file to which the system writes swapped portions of memory. The OpenVMS installation procedure creates a swap file named SYS$SYSTEM:SWAPFILE.SYS.
Primary page and swap files
The default page and swap files created during OpenVMS installation. These files are named SYS$SYSTEM:PAGEFILE.SYS and SYS$SYSTEM:SWAPFILE.SYS.
Secondary page and swap files
Additional page and swap files that you might create for performance or disk space reasons. If you kept the primary page and swap file on the system disk, the system uses the space in the secondary files for paging and swapping in addition to the space in the primary page and swap files. For information about creating secondary page and swap files, see Creating and Modifying Page, Swap, and Dump Files.

Installing Files

Page and swap files must be installed before the system can use them. The system automatically installs the latest versions of SYS$SYSTEM:PAGEFILE.SYS and SWAPFILE.SYS during startup. If you create secondary page and swap files, you must make sure the system installs them during startup. For more information about installing page and swap files, see Installing Page and Swap Files.

File Sizes and Locations

AUTOGEN automatically determines appropriate sizes for the files for your hardware configuration and system parameters. For special configurations or varying work loads, you might want to change the size of the page or swap file. For information, see Using AUTOGEN (Recommended Method).

If your system does not require the page file for storing system crash dumps, you can move it off the system disk. However, you should keep one page file on the system disk, if possible, so that you can boot the system if another disk holding the page files becomes unavailable. The swap file can also be moved off the system disk.


go to previous page: Understanding Dump Files Understanding Dump Files
go to next page: Displaying Information About Page and Swap FilesDisplaying Information About Page and Swap Files