A scenario :

windows xp 32bit, oracle 10.2.0.1 -32bit.

1, alter system set processes=15 scope=spfile ;

2 restart oracle ,Can only mounted, but not be able to open.

3, alter system set processes=20 scope=spfile ;

4, open database successfully.

[@more@]

A scenario :

windows xp 32bit, oracle 10.2.0.1 -32bit.

1, alter system set processes=15 scope=spfile ;

2 restart oracle ,Can only mounted, but not be able to open.

3, alter system set processes=20 scope=spfile ;

4, open database successfully.

5,SQL> select count(*) from v$session ;

COUNT(*)
----------
16

SQL> select count(*) from v$process ;

COUNT(*)
----------
19

6, at this time ,Add a new Login from sqlplus , but it's pending.

so I say , 20 processes only have 19 useable processes.

Also I found another new interesting question.

step 6, is not seriously right , because if you login as sysdba , you can Did login and pop-up information appearing as normal.

But In dead. If you issue a comand such as select or dml operation in succession. You will find you had be kick out but with nothing hint.

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A question about processes parameter