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46.2.3.3. 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 core collector, open the /etc/kdump.conf configuration file as root, remove the hash sign (#) from the beginning of the #core_collector makedumpfile -c --message-level 1 line, and edit the command line options as described below.
To enable the dump file compression, add the -c parameter. For example:
core_collector makedumpfile -c
To remove certain pages from the dump, add the -d value parameter, where 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 the following:
core_collector makedumpfile -d 17 -c
Refer to the manual page for makedumpfile for a complete list of available options.

Table 46.1. Supported filtering levels

Option Description
1 Zero pages
2 Cache pages
4 Cache private
8 User pages
16 Free pages