File extension .sf

These system files are indexes and descriptors of the files on the VMFS filesystem and cannot be deleted.

They may take more space if you have a small block size (more addresses).
They are metadata files that are created when the volume is first set up.
They cannot be changed and cannot be deleted.
They may grow over time but not significantly.

    fbb.sf - file block bitmap.system file
    fdc.sf - file descriptor cluster.system file
    pbc.sf - pointer block cluster.system file
    sbc.sf - sub-block cluster.system file
    vh.sf - vmfs heartbeat.system file
    sdd.sf scsi device description.system file
    pb2.sf - pointer block 2.system file