Bringing up Online on NCR- MP RAS

Dear Folks, I would appreciate any feedback for the following puzzling situation: I have following error when starting Online engine. Informix Online 5.10.UC1 NCR 3000 series with MP-RAS V3.0 Following is the error reported on the screen: tbinit: Fatal error in shared memory initialisation 14:33:55 semop failed. errno:36, proc id 1951 Following is the entry in the log file: 14:33:55 I/O error 'read': expect 2048 actual -1 addr 0x0 errno 6 retrys 0 14:33:55 I/O error 'read': expect 2048 actual -1 addr 0x0 errno 6 retrys 1 14:33:55 I/O error , Primary Chunk '/dev/rdsk/rootdbs' -- Offline 14:33:55 I/O read() chunk 1, pagenum 0, pagecnt 1 --> errno=6 14:33:55 INFORMIX - Online Must Abort Root chunk down 14:33:55 -- Online aborting -- us=400024e4, pid=1950, uid=10614:33:55 INFORMIX-Online Stopped I tried to re-initalise the instance, tbinit -i, but faced the same. Kernel parameters are OK and tuned according to the release file. Am I missing anything ? Thanks in advance, Sandeep