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A Red Hat training course is available for Red Hat Enterprise Linux Configuring the Core Collector

To reduce the size of the vmcore dump file, kdump allows you to specify an external application (that is, a core collector) to compress the data, and optionally leave out all irrelevant information. Currently, the only fully supported core collector is makedumpfile.
To enable the dump file compression, make sure the -c parameter is listed after the makedumpfile command in the Core Collector field (for example, makedumpfile -c).
To remove certain pages from the dump, add the -d value parameter after the makedumpfile command in the Core Collector field. The value is a sum of values of pages you want to omit as described in Table 46.1, “Supported filtering levels”. For example, to remove both zero and free pages, use makedumpfile -d 17.
Refer to the manual page for makedumpfile for a complete list of available options.