What is stored in the /tmp/mmfs directory and why does it sometimes disappear?
When GPFS encounters an internal problem, certain state information is saved in the GPFS dump directory for later analysis by the IBM® Support Center.
The default dump directory for GPFS is /tmp/mmfs.
This directory might disappear on Linux if
cron is set to run the /etc/cron.daily/tmpwatch script.
The tmpwatch script removes files and directories
in /tmp that have not been accessed recently.
Administrators who want to use a different directory for GPFS dumps can change the directory by issuing
this command:
mmchconfig dataStructureDump=/name_of_some_other_big_file_systemNote: This state information (possibly large amounts of data in
the form of GPFS dumps and traces)
can be dumped automatically as part the first failure data capture
mechanisms of GPFS, and can
accumulate in the (default /tmp/mmfs) directory
that is defined by the dataStructureDump configuration
parameter. It is recommended that a cron job (such as /etc/cron.daily/tmpwatch)
be used to remove dataStructureDump directory
data that is older than two weeks, and that such data is collected
(for example, via gpfs.snap) within two weeks of
encountering any problem that requires investigation.