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.
Note: You must not remove the contents of the callhome subdirectory in
dataStructureDump. For example, /tmp/mmfs/callhome. Call
Home automatically ensures that it does not take up too much space in the
dataStructureDump directory. If you remove the call home files, the copies of
the latest uploads are prematurely removed, which reduces the usability of the
mmcallhome command. For example, mmcallhome status
diff.