Obtaining a dump with limited size
The mem kernel parameter can make Linux® use less memory than is available to it. A dump of a Linux system like this does not need to include the unused memory. You can use the zipl size option to limit the amount of memory that is dumped.
About this task
This section does not apply to kdump.
The size option is available for all zipl based dumps except SCSI: DASD and tape, in command line mode, or in configuration file mode. The size option is appended to the dump device specification with a comma as separator.
The value is a decimal number that can optionally be suffixed with K for kilobytes, M for megabytes, or G for gigabytes. Values specified in byte or kilobyte are rounded to the next megabyte boundary.
Be sure not to make the dump size smaller than the amount of memory actually used by the system to be dumped. Limiting the dump size to less than the amount of used memory results in an incomplete dump.
Example
# zipl -d /dev/dasdc1,100MAn equivalent section in a configuration file could look like this:
[dump1]
dumpto=/dev/dasdc1,100M