Kernel-Managed Swap Facility (KMSF) Manual

NSKCOM Command Reference

Kernel-Managed Swap Facility (KMSF) Manual—425824-005

4-5

ALT[ER] Command

The ALTER command changes attributes of a swap file. Modifiable attributes are

MAXEXTENTS, SIZE, and THRESHOLD. This command can be issued only by

super-group users (255, n).

filename

is the name of the swap file to be altered. The variable filename is specified as:

$volume.subvolume.filename.

attribute value

optionally sets the value of an attribute of the swap file. The attribute can be EXT,

MAXEXTENTS, SIZE, THRESHOLD, or FORMAT. For the set of attributes EXT,

MAXETENTS, and SIZE, it is not necessary to specify values for all three

attributes. If two of these attributes are specified or assumed (see the ASSUME

Command on page 4-8), the third value is calculated.

The values are specified as follows:

EXT[ENT[s]] disk-pages-per-extent

specifies the number of disk pages per extent.

This value must be a multiple of the processor memory page size

(16 kilobytes). If you specify less than what is required, the value is rounded up

to the required value.

The default disk pages per extent is 512 (1 megabyte) for G-series RVUs and

1024 (2 megabytes) for H-series RVUs. The minimum is 8 pages, but using the

minimum value is not recommended.

For Format 1 files, you can specify a value up to 65504. However, because of

32-bit addressing, Format 1 files are limited to a maximum size of

2047 megabytes, where:

2047= EXTENTS * MAXEXTENTS * 2048 bytes.

The maximum value for Format 2 files is 65536.

MAX[EXTENT[S]] maximum-extents

specifies the maximum number of extents for the file.

For both Format 1 and Format 2 files:

•

The minimum value is 16

•

The default value is 64

ALT[ER] SWAPF[ILE] filename attribute value [, attribute

value ]