maxswapchunks

maxswapchunks sets the maximum amount of swap space that can be configured, system-wide.

Acceptable Values:

Minimum

1

Maximum

16384

Default

256

Specify integer value. For more information, see Specifying Parameter Values.

Description

maxswapchunks specifies the maximum amount of configurable swap space on the system. The maximum swap space limit is calculated as follows:

• Disk blocks contain DEV_BSIZE (1024) bytes each. DEV_BSIZE is the system-wide mass storage block size and is not configurable.

• Swap space is allocated from device to device in chunks, each chunk containing swchunk blocks. The value of swchunk should not be changed from the standard default value.

• The maximum number of chunks of swap space allowed system-wide is maxswapchunks chunks.

• The maximum swap space in bytes is:

  maxswapchunks times swchunk times DEV_BSIZE

  For example, using default values for swchunk (2048) and maxswapchunks (256), and assuming DEV_BSIZE is 1024 bytes, the total configurable swap space equals 537 Mbytes.

Selecting Values

The amount of swap space available on system disk devices is determined by the contents of file /etc/fstab, and is not affected by kernel configuration.

On a stand-alone system or on a cluster client with local swap space, maxswapchunks should be set to support sufficient swap space to accommodate all swap anticipated. Set the parameter large enough to avoid having to reconfigure the kernel.

For a server node, set the parameter to include not only the server's local swap needs, but also sufficient swap for each client node that will use the swap. At a minimum, allot swap space equal to the amounts of memory used by each client.

Related Parameters

The total configurable swap space is defined by:

maxswapchunks times swchunk times 1024 bytes

System-imposed maximum total swap space is approximately 34 Gbytes.

Additional Information

• Overview of paging parameters
• List of paging parameters
• Browse configurable kernel parameters help