Hi Gaurav,
One more thing.... we are facing this problem on one application node only. From other node, it is working fine.
I assume the problem is on the node where DB is not installed ?
In such a case check your environment parameters once again. Especially path of SAP executables.
Secondly check listener.ora entries. I feel hostname would have been maintained in the file and it takes time to cache the hostname. Change it to IP address and check the results.
For backups getting failed check the RFC destination connection SAPXPG_DB_XXX from the application node. Ensure correct gateway host is maintained.
Hope this helps.
Regards,
Deepak Kori