controller means for updating, via non concurrent clock cycles, {HEAD ~ the associated mirror image data validity status information} in said {TAIL ~ first directory} means 
in
controller means for updating , via non concurrent clock cycles , { HEAD ~ the associated mirror image data validity status information } in said { TAIL ~ first directory } means
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH