MPI fail due to insufficient space

If you encounter an error that cause your MPI run to fail, such as the one below, it is due to the /tmp not having sufficient space  

[node1:25646] [[31090,0],0] ORTE_ERROR_LOG: Error in file orterun.c at line 543
Number of requested processors =  8
[node1:25663] opal_os_dirpath_create: Error: Unable to create the sub-directory 
(/tmp/openmpi-sessions-user1@node1_0) of (/tmp/openmpi-sessions-user1@node1_0/31075/0/0), mkdir failed [1]
[node1:25663] [[31075,0],0] ORTE_ERROR_LOG: Error in file util/session_dir.c at line 106
[node1:25663] [[31075,0],0] ORTE_ERROR_LOG: Error in file util/session_dir.c at line 399
[node1:25663] [[31075,0],0] ORTE_ERROR_LOG: Error in file ess_hnp_module.c at line 304

The solution is to clean up the /tmp or the partition where /tmp is residing. You can choose the "df -h" at the console to verify that your HDD space

# df -h