Oracle 9i Enterprise Edition
SQL> show parameter dispa

------------------------------------ ----------- ------------------------------
dispatchers string (PROTOCOL=TCP) (dispatchers=2)
max_dispatchers integer 5
mts_dispatchers string (PROTOCOL=TCP) (dispatchers=6)
mts_max_dispatchers integer 5

Now i alter the dispatchers to 3 in both memory and spfile and it is successful:
SQL> alter system set dispatchers = '(PROTOCOL=TCP) (dispatchers=3)';

System altered.

But when i want to alter the "dispatchers" parameter only in spfile, the following errors occur:
SQL>alter system set dispatchers = '(PROTOCOL=TCP) (dispatchers=4)' scope=spfile;
alter system set dispatchers = '(PROTOCOL=TCP) (dispatchers=4)' scope=spfile
ERROR at line 1:
ORA-02065: illegal option for ALTER SYSTEM
I was confused about the error tips, Any one knows ?
Thanks in advance