[Oracle10g] minimum value of the processes parameter when dbca creates a database

When dbca creates a database, the default value of the processes parameter is 150. Generally, it does not have to worry about the minimum value, but the minimum value is 6 in "2 daydba" and "dbca, it includes several background processes that must be started for the database instance. Five background processes, plus at least one user process, are equivalent to six. However, according to the previous blog, set to 6 Yes

When dbca creates a database, the default value of the processes parameter is 150. Generally, it does not have to worry about the minimum value, but the minimum value is 6 in dbca and dbca, it includes several background processes that must be started for the database instance. Five background processes, plus at least one user process, are equivalent to six. However, according to the previous blog, set to 6 Yes

When dbca creates a database, the default value of the processes parameter is 150. Generally, the minimum value of the parameter is not concerned, but the minimum value in dbca and dbca seems to be 6, it includes several background processes that must be started for the database instance. Five background processes, plus at least one user process, seem to be 6. But according to the previous blog, set to 6 is inevitable, the error ora-03113, new cannot be completed, then the actual minimum value is how much? Maybe no one cares about this, and I'm just curious.

Verify that the environment is oracle10.2 in windows. First, I tried to specify the value of the processes to be tried by recreating the database, and thought how stupid I was. Why not alter system set processes = int, at first, an error was reported, prompting that the parameter could not be modified. Later, I thought that the scope option was not added, and I tried to add scope = both. The result still returned an error, so that I realized that this is a static parameter, only scope = spfile can be used for modification, and the modification will take effect after restart.

So I tried several values and found that the database could not be opened at the processes value of 20 or a dozen, but only to the mount stage. However, I forgot to close other connections at this time. When the value is 30, the database can be opened normally. This is to verify the connection limit of this parameter by constantly increasing client connections: use SQL> select count (*) from v $ process to view the current number of connections, when the number reaches 29, the user cannot be connected. However, when the user is connected to sysdba, the user can be connected, but the above query result is still 29. In the latest verification, it is found that "connect to idle routine" is displayed after sysdba is connected, and database operations cannot be performed. No matter how many connections, the connection is limited when the number of connections reaches the specified value-1.

At this time, we thought we could shut down all the clients, restart the database, and in the nomount phase, we found that the current number of connections is 15, the mount phase is still 15, and then to the open state, which is 19, it is preliminarily inferred that the minimum number of connections required is 19. After multiple restart, this value is still used. Finally, the processes value is changed to 20. The database is started successfully and the current connection value is 19. Finally, change the value of processes to 19 and restart the database. When I think that the actual minimum value is 19, the database is restarted successfully. The current connection count is 18! Continue to change the processes value to 18, restart the database, finally found not open, prompt ora-01092: oracle instance terminated. In this case, the processes can be opened normally when it is changed to a relatively large number of connections. After it is opened, the current number of connections is 23.

To sum up, the processes parameter determines the maximum number of connections of the oracle service, including the database background process and user process, and the server process may also include. To enable the database to start normally (10g enterprise edition in windows), the minimum value of this parameter is near 19.