AutoConfig with SCAN : Services Fail to Register to SCAN Listeners

This issue might occur in an environment where RAC / SCAN was configured and where the Applications or E-Business Suite utility AutoConfig was used to configure the database environment. This issue might also occur when a customer attempts to use a TNS connect string (versus the EZCONNECT setting) for REMOTE_LISTENER where the single SCAN address is specified.

Solution

1) Find and eliminate the TNS_ADMIN/tnsnames.ora file entry that was created by AutoConfig:

SCANHOST:1521 =
   (DESCRIPTION=
     (ADDRESS_LIST=
      (ADDRESS=(PROTOCOL=tcp)(HOST=SCANHOST)(PORT=1521))
     )
   )

Once this is done, PMON won't find the entry in tnsnames and will search the correct adapter EZCONNECT for resolution.

2)  Set the following sqlnet.ora file parameter in the database's environment so that PMON does not use the TNSNAMES adapter first.  This would require a restart of the instance as PMON will need to read sqlnet.ora on startup.

NAMES.DIRECTORY_PATH=(EZCONNECT,TNSNAMES)

3)  If using a tnsnames.ora file entry for the REMOTE_LISTENER setting in SCAN is necessary or desirable, it must be configured with all SCAN ip addresses.

e.g.

REMOTE_LISTENERS_SCAN=
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = xx.xx.xx.13)(PORT = 1521))
      (ADDRESS = (PROTOCOL = TCP)(HOST = xx.xx.xx.14)(PORT = 1521))
      (ADDRESS = (PROTOCOL = TCP)(HOST = xx.xx.xx.15)(PORT = 1521))
    )

SQL>Alter system set REMOTE_LISTENER='REMOTE_LISTENERS_SCAN' scope=both sid='*';
SQL>Alter system register;