S and T File Permissions

HDF5 Library
1

Can HDF5 cause special group id and stick bits on files?

I’ve got a code writing multiple hdf5 files in parallel to a gpfs file system using the H5FD_MPIO_COLLECTIVE_F mode. Many of the files have the correct permissions but several come out with special group id “S” and sticky bit “T” set. It’s always the same files that come out this way. Can HDF5 cause this to happen? If so what is the cause?

File permissions look like this (1 good + 1 with S&T):

-rwx—— 1 myuser 8236GYH2 2116760 Nov 18 19:10 ci_restart_E04_PT00H04M.hdf5

-rwx–S–T 1 myuser 8236GYH2 2116760 Nov 18 19:10 ci_restart_E04_PT00H06M.hdf5

3

HDF5 does not explicitly set the Set Group ID (setgid) or Sticky bits on files. Instead, it relies on standard MPI-IO or POSIX file creation drivers. No function in the public HDF5 API is designed to manipulate these specific bits.