Kernel-Managed Swap Facility (KMSF) Manual

NSKCOM Command Reference
Kernel-Managed Swap Facility (KMSF) Manual—425824-005
4-6
ALT[ER] Command
For Format 1 files, you can specify a maximum value up to 800. However,
because of 32-bit addressing, Format 1 files are limited to a maximum size of
2047 megabytes, where:
2047= EXT * MAXEXTENTS * 2048 bytes.
For Format 2 files, the maximum value is 800.
If each extent is 1 megabyte (512 disk pages), then MAXEXTENTS is
equivalent to SIZE.
SIZE filesize {KB | MB | GB | PAGES}
specifies the size of the file, where SIZE = EXT * MAXEXTENTS * 2048 bytes.
KB, MB, and GB are abbreviations for 1,024, 1,048,576, and 1,073,741,824
bytes respectively. PAGES is the number of memory pages (not disk pages).
The entered value is rounded up to make the extent size a multiple of
processor page size, if necessary.
The default file size for a configured swap file is 64 megabytes, fully allocated.
The minimum file size is 256 kilobytes, but using the minimum value is not
recommended.
The maximum size for a Format 1 swap file is 2047 megabytes.
The maximum size for a Format 2 swap file is 100 gigabytes.
If each extent is 1 megabyte (512 disk pages), then SIZE is equivalent to
MAXEXTENTS.
THRESH[OLD] percent-full
is the percent in-use monitoring value for a swap file. If usage exceeds the
threshold, an Event Management Service (EMS) event is generated.
Exceeding the threshold value does not prevent usage of the swap file.
The minimum threshold is 1 percent.
The default threshold is 85 percent.
The maximum threshold is 100 percent.
FORMAT {0 | 1 | 2}
specifies the type of swap file format to be used. When format 0 is specified on
the command line, the system chooses the file format to be used, based on the
file’s size parameters. See Table 1-1 on page 1-9 to see how the values of
extents, maxextents, and size change according to the format of the swap file
used.
In Example 4-2 on page 4-7, the threshold of the swap file is altered to 75 percent.