Managing Core Files

The Linux core_pattern file (in /proc/sys/kernel/core_pattern) can be used to specify the location for storing core files. If any process launched by MapR crashes, the core files are created in the directory specified by the core_pattern file. A valid location in the core_pattern file is a full path to the directory you want to use. For example:

Tip: For details about the standard Linux % specifiers that you can use to name core files, see the core man page.

If the core_pattern file is empty, if the file does not contain a full path, or if it uses the "|" redirection feature, by default, MapR sets the location for core files (in the event of a core dump on a node) to /opt/cores directory when:

  • The utility is run.
  • The Warden init script is run.
  • The MFS init script is run by Warden.

The default directory (/opt/cores) is also used if the core_pattern file contains the default MapR value for core files.

For MapR software, the directory being used to store core files should not be used for other purposes and should be empty. The cores directory cannot be home directory because it can cause problems during SSH access. The hoststats service monitors the directory specified in the core_pattern file and raises the node-level alarm if the directory contains any entry other than "." and "..". When Warden is started, sticky bit is set on the cores directory.