The PROCESSES initialization parameter affects Oracle ASM, but the default value is usually suitable. However, if multiple database instances are connected to an Oracle ASM instance, then you can use the following formulas, where n is the number of database instances connecting to the Oracle ASM instance.
In a non-Exadata environment, the recommended settings are:
For n < 10, PROCESSES = 50*n + 50
For n >= 10, PROCESSES = 10*n + 450
In an Oracle Exadata environment, the recommended setting is PROCESSES = MAX(450 + 10*n, 1024).
Oracle Database Administrator's Guide for more information about setting the PROCESSES initialization parameter
Oracle Database Reference for more information about the PROCESSES parameter