ORA-12518 TNS: Solution for listeners failing to distribute client connections

1. GLOBAL_DBNAME and SID_NAME In the listener file may not match the Instance name. After modification, restart listener.
2. The value of processes in VPC mode is too small. You can solve this problem by using the following methods:
1. cmd
2. sqlplus
3. connect sys/test as sysdba
4. view the number of sessions, processes, and sessions.
SQL> select count (*) from v $ session;
COUNT (*)
 
----------
45
SQL> show parameter processes
NAME TYPE VALUE
Db_writer_processes integer 1
Gcs_server_processes integer 0
Job_queue_processes integer 10
Log_archive_max_processes integer 2
Processes integer 50

SQL> show parameter sessions
NAME TYPE VALUE
Java_soft_sessionspace_limit integer 0l
Icense_max_sessions integer 0
License_sessions_warning integer 0
Logmnr_max_persistent_sessions integer 1
Sessions integer 60
Shared_server_sessions integer
5. Modify the values of processes and sessions: sessions = (1.1 * process + 5)
SQL> alter system set processes = 300 scope = spfile;
The system has been changed.
SQL> alter system set sessions = 335 scope = spfile;
The system has been changed.
6. Restart the database to make the change take effect.
Iii. Sharing Mode
1. show parameters dispatchers;
NAME TYPE VALUE
Dispatchers string (protocol = tcp) (service = oracle10xdb)
Max_dispatchers integer
2. check whether there are enough dispatchers.
SQL> select name, (busy/(busy + idle) "dispatcher busy rate" from v $ dispatcher;
NAME dispatcher busy rate
------------------------
D000. 000121704
D001. 000042597
D002. 004935402
If it exceeds 50%, you need to consider adding more dispatchers;
3. Change dispathchers:
SQL> alter system set dispatchers = '(protocol = tcp) (dispatchers = 3) (service = oracle10xdb )';
System altered
4. the PGA memory is too small.
Note: This method has not been tried.

Author: ERDP Technical Architecture"