Hi Balaji, have you tried to use no_squash options?
Can you share with us the NFS options you're using? Is the NFS server also running on Linux? We might be able to compare your settings with the recommendations given in the installation guide and internal systems .
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Please note that you should 'export' the sapmnt directory as described in the guide. For your reference, please download the guide at:
http://www.service.sap.com/sltoolset -> Software Logistic Toolset 1.0 -> [Scroll down the page] Software Provisioning Manager -> Installing Systems Based on NW 7.1 or Higher-SW Prov.Mgr.1.0
Please follow as descrined in section "5.3 Exporting and Mounting Global Directories".
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See also
http://help.sap.com/saphelp_nw70ehp2/helpdata/en/0a/0a2e39ef6211d3a6510000e835363f/frameset.htm
https://service.sap.com/sap/support/notes/2093132
Regards,
Americo