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;