There you go sumit.
/usr/sap/PRD/ASCS01/exe/sapstart=>sapparam: SAPSYSTEMNAME neither in Profile nor in Commandline
**** unknown SAPSYSTEMNAME.
(29859) Exiting with Return-Code -101. (Unknown Sap-System-Name)
Startup of Instance failed
please verify and correct the SAPSYSTEMNAME parameter in your instance, default and startup profile.
SAPSYSTEMNAME = your SID
SAPGLOBALHOST = your HOSTNAME. (you have already mentioned this right)
RESTART
Regards,
Nag.