i am working properly in portal but some time an error automatically arise
503 Service Unavailable 7.00
SAP WebAS Engine is starting...
If this state does not change within a few minutes,
please contact your system administrator.
Check the recommendations in SAP Notes: 943498, 764417
Message: Dispatcher running but no server connected!
Details: No details available
and i increase the heap memory to 2 gb in server0 file permsize to 512 mb as sujeested by some experts
but i got the same problem again after some time