Folks Manually converted a Database from NON-RAC to RAC (2 instances) & Changed the "tnsnames.ora" file suitably. Yet connect VIA the Listener to this Database is failing. ERROR: ORA-12521: TNS:listener does not currently know of instance requested in connect descriptor NOTE - Connect to another Sample Database (TSTRAC) Created thru the "DBCA" Tool on the Same RAC Nodes is successful. Qs Is registering of this RAC database and its instance-to-node mapping using SRVCTL needed? If so, How? Qs Is Manually Change to some Other files also needed (Other than tnsnames.ora)? Thanks indeed FAILING Database PNBRAC related services versus TSTRAC (Working Database) related services are shown below:- $ lsnrctl stat Service "PNBRAC.ad.infosys.com" has 1 instance(s). Instance "PNBRAC", status READY, has 1 handler(s) for this service... Service "PNBRACXDB.ad.infosys.com" has 1 instance(s). Instance "PNBRAC", status READY, has 1 handler(s) for this service... Service "PNBRAC_XPT.ad.infosys.com" has 1 instance(s). Instance "PNBRAC", status READY, has 1 handler(s) for this service... Service "TSTRAC.ad.infosys.com" has 2 instance(s). Instance "TSTRAC1", status READY, has 2 handler(s) for this service... Instance "TSTRAC2", status READY, has 1 handler(s) for this service... Service "TSTRACXDB.ad.infosys.com" has 2 instance(s). Instance "TSTRAC1", status READY, has 1 handler(s) for this service... Instance "TSTRAC2", status READY, has 1 handler(s) for this service... Service "TSTRAC_XPT.ad.infosys.com" has 2 instance(s). Instance "TSTRAC1", status READY, has 2 handler(s) for this service... Instance "TSTRAC2", status READY, has 1 handler(s) for this service... **************** CAUTION - Disclaimer ***************** This e-mail contains PRIVILEGED AND CONFIDENTIAL INFORMATION intended solely for the use of the addressee(s). If you are not the intended recipient, please notify the sender by e-mail and delete the original message. Further, you are not to copy, disclose, or distribute this e-mail or its contents to any other person and any such actions are unlawful. This e-mail may contain viruses. Infosys has taken every reasonable precaution to minimize this risk, but is not liable for any damage you may sustain as a result of any virus in this e-mail. You should carry out your own virus checks before opening the e-mail or attachment. Infosys reserves the right to monitor and review the content of all messages sent to or from this e-mail address. Messages sent to or from this e-mail address may be stored on the Infosys e-mail system. ***INFOSYS******** End of Disclaimer ********INFOSYS***