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Due to historical reasons, application upgrade costs. Recently, a new set of oracle 10g RAC (10.2.0.5) was installed. During the test, the database was linked from other application servers using vip links. A large number of errors were found and reported as ora-12545 because the target host or object does not exist.

ORA-12545: Connect failed because target host or object does not exist

Query online materials and mos documents

The cause of the problem

Whe LOCAL_LISTENER is not set at all or is not set correctly, PMON can register both the VIP hostname and the physical hostname with the REMOTE_LISTENER. This is incorrect in RAC but if it does occur, the client can intermittently be routed to a listener endpoint on either of these addresses. If the client is unable to resolve the physical hostname or even the vip hostname, the connection will fail with ORA-12545.

Because LOCAL_LISTENER is not configured or does not strive for configuration, the PMON process uses REMOTE_LISTENER to register vip hostname and physical addresses. In rac, this is the wrong configuration, and the client cannot use these addresses to route to the listening server correctly. If the client fails to resolve the physical address or the hostname of vip correctly, the link will report an ORA-12545 error.

Additionall, if the VIP hostname cannot be resolved, but the VIP numerical address is reachable; then this VIP numerical address should be used as the HOST value for LOCAL_LISTENER instead.

And important first set is to check the output for: lsnrctl services

You should not see the physical hostname in the handler information for your RAC instances. Here's an example of an incorrect lsnrctl services output for a 2-node RAC cluster:

Lsnrctl services oracle_rac_listener

Service "oracle.oracle.com" has 2 instance (s).

Instance "orcl1", status READY, has 2 handler (s) for this service...

Handler (s):

"DEDICATED" established:0 refused:0 state:ready

REMOTE SERVER

(ADDRESS= (PROTOCOL=TCP) (HOST=myphysicalhost1) (PORT=1521))

"DEDICATED" established:326 refused:0 state:ready

LOCAL SERVER

Instance "orcl2", status READY, has 1 handler (s) for this service...

Handler (s):

"DEDICATED" established:394371 refused:0 state:ready

REMOTE SERVER

(ADDRESS= (PROTOCOL=TCP) (HOST=myphysicalhost2) (PORT=1521))

Here's an example of what it ought to look like when LOCAL_LISTENER is configured correctly:

Lsnrctl services oracle_rac_listener

Service "oracle.oracle.com" has 2 instance (s).

Instance "orcl1", status READY, has 2 handler (s) for this service...

Handler (s):

"DEDICATED" established:0 refused:0 state:ready

REMOTE SERVER

(ADDRESS= (PROTOCOL=TCP) (HOST=myVIP_host1) (PORT=1521))

"DEDICATED" established:326 refused:0 state:ready

LOCAL SERVER

Instance "orcl2", status READY, has 1 handler (s) for this service...

Handler (s):

"DEDICATED" established:394371 refused:0 state:ready

REMOTE SERVER

(ADDRESS= (PROTOCOL=TCP) (HOST=myVIP_host2) (PORT=1521))

Solution:

Modify the LOCAL_LISTENER configuration of the RAC instances on both sides.

Alter system set LOCAL_LISTENER= "(address= (protocol=tcp) (port=1521) (host=))" scope=both sid='INSTANCE_NAME1'

Alter system set LOCAL_LISTENER= "(address= (protocol=tcp) (port=1521) (host=))" scope=both sid='INSTANCE_NAME2'

In addition, the related configuration REMOTE_LISTENER.

Alter system set REMOTE_LISTENER='' scope=both sid='*'

In addition, parallel_instance_group parameters can also be configured with different values.

Alter system set parallel_instance_group= "A" scope=both sid='INSTANCE_NAME1'

Alter system set parallel_instance_group= "B" scope=both sid='INSTANCE_NAME2'

Finally, note that after modification, restart listening. If restarting listening does not work, restart the database or restart two instances.

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