The Oracle Parameter
Processes
PROCESSES DEFINITION
Parameter type | Integer |
Default value | Derived from |
Parameter class | Static |
Range of values | 6 to operating system-dependent |
Real Application Clusters | Multiple instances can have different values. |
PROCESSESspecifies the maximum number of operating system user processes that can simultaneously connect to Oracle. Its value should allow for all background processes such as locks, job queue processes, and parallel execution processes.
The default values of the SESSIONS and TRANSACTIONS parameters are derived from this parameter. Therefore, if you change the value of PROCESSES, you should evaluate whether to adjust the values of those derived parameters.
http://docs.oracle.com/cd/B10501_01/server.920/a96536/ch1168.htm#REFRN10175
Specifying the Maximum Number of Processes
The PROCESSESinitialization parameter determines the maximum number of operating system processes that can be connected to Oracle Database concurrently. The value of this parameter must be a minimum of one for each background process plus one for each user process. The number of background processes will vary according the database features that you are using. For example, if you are using Advanced Queuing or the file mapping feature, you will have additional background processes. If you are using Automatic Storage Management, then add three additional processes for the database instance.
If you plan on running 50 user processes, a good estimate would be to set the PROCESSESinitialization parameter to 70.
http://docs.oracle.com/cd/B28359_01/server.111/b28310/create005.htm#ADMIN11108
SAP Notes:
34432 - ORA-00020: maximum number of processes exceeded
SAP Notes for Recommended Oracle Parameters:
830576 - Parameter recommendations for Oracle 10g
1431798 - Oracle 11.2.0: Database Parameter Settings
Error Captured:
Backup Failed: http://scn.sap.com/thread/1398677
Archival failed with below reasonhttp://scn.sap.com/thread/1251972
Solution Manager crashes every two week or so:http://scn.sap.com/thread/3333727
Background jobs failed http://scn.sap.com/thread/1980217
Database check failed: http://scn.sap.com/thread/1226748
Transport Terminated: http://scn.sap.com/thread/461606
Error in Portal System: http://scn.sap.com/thread/18638
Check Current Value of Processes:
ST04 / DBCOCKPIT Transaction
SPFILE Entry in ST04
Current Used Processes Value
Compare the PIDs on task manager
Calculation of Processes by Hardware of System:
Parallel_max_servers calculation
PARALLEL_MAX_SERVERS depends on the CPU cores in the database server available for database (total CPU cores on database server minus CPU requirements of other applications including SAP central instance)
PARALLEL_MAX_SERVERS = Number of DB machine CPU CORES*10
For example for ABAP Stack:
Number of CPU = 4
Parallel_Max_Servers = 4 * 10 = 40
ABAP Work Processes = 25
Processes = (ABAP Work Processes * 2) + Parallel_Max_Servers + 40 = (25*2) + 40 + 40 = 130
Session = 2 * Processes = 260
For example for JAVA Stack
PROCESSES = J2EE server processes * <max-connections> + PARALLEL_MAX_SERVERS + 40
J2EE Server Processes = 2 (if two server nodes – Server0 and Server1)
Max Connections = Open the Visual Administrator and select Server <X> -> Services -> JDBC Connector = 50
PROCESSES = 2*50 + 40 + 40 = 180
Session = 180 * 2 = 360
SESSIONS CALCULATION:
SESSIONS | 2 * PROCESSES |