Hi Jeetendra,
Check whether you system is up and running ?
If yes, then sapdata3 is a folder created under /oracle/SID or /oracle based on your file system structure.
As right mentioned SAP installer will not create any file system. If file system /oracle/SID/sapdata3 is not available, SAP installer will create a folder sapdata3 under /oracle/SID and respective data files will be created under the same.
Hope this helps.
Regards,
Deepak Kori
