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$SYSTEM:SWAPFILE.SYS.
|
Secondary page and
swap files
|
Additional page and swap files that you
might create for performance or disk space reasons. If you kept
the primary page and swap file on the system disk, the system uses
the space in the secondary files for paging and swapping in addition to
the space in the primary page and swap files. For information about
creating secondary page and swap files, see
Creating and Modifying Page, Swap, and Dump Files.
|
Page and swap files must be installed before the system can
use them. The system automatically installs the latest versions
of SYS$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.
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.