ORA-00020: maximum number of processes exceeded

ORA-00020: maximum number of processes

This error occurs when your total numbers of sessions connecting to oracle database has exceeded the max limit set in parameter file. Simplest way to overcome this error is to reset the max sessions value to a greater value than existing.Here is how to do it
 



oracle@LINUX201:[~] $ sqlplus / as sysdba

SQL*Plus: Release 11.2.0.4.0 Production on Mon Jun 13 10:20:26 2016

Copyright (c) 1982, 2013, Oracle.  All rights reserved.

ERROR:
ORA-00020: maximum number of processes (500) exceeded



oracle@LINUX201:[~] $ sqlplus / as sysdba

SQL*Plus: Release 11.2.0.4.0 Production on Mon Jun 13 10:23:42 2016

Copyright (c) 1982, 2013, Oracle.  All rights reserved.

ERROR:
ORA-00020: maximum number of processes (500) exceeded

Enter user-name:

Disconnected from ORACLE

I wasn't able get into the oracle database to kill some database session. So I tried to kill few sessions on OS to make my way into DB.

oracle@LINUX201:[~] $ ps -ef|grep oracle
.
.
.
.
.
.
.

oracle   64373     1  0 Jun08 ?        00:00:03 oracleQPDEV (LOCAL=NO)
oracle   64540     1  0 Jun08 ?        00:00:00 oracleQPDEV (LOCAL=NO)
oracle   64554     1  0 Jun08 ?        00:00:01 oracleQPDEV (LOCAL=NO)
oracle   64633     1  0 Jun08 ?        00:00:03 oracleQPDEV (LOCAL=NO)
oracle   64637     1  0 Jun08 ?        00:00:00 oracleQPDEV (LOCAL=NO)
.
.
.
oracle   65186     1  0 Jun08 ?        00:00:04 oracleQPDEV (LOCAL=NO)
oracle   65190     1  0 Jun08 ?        00:00:00 oracleQPDEV (LOCAL=NO)
oracle   65192     1  0 Jun08 ?        00:00:01 oracleQPDEV (LOCAL=NO)
oracle   65202     1  0 Jun08 ?        00:00:00 oracleQPDEV (LOCAL=NO)
oracle   65206     1  0 Jun08 ?        00:00:02 oracleQPDEV (LOCAL=NO)
root     65407 65381  0 May16 pts/2    00:00:00 sudo -u oracle -i
oracle   65408 65407  0 May16 pts/2    00:00:00 -bash
oracle   65458 65408  0 May16 pts/2    00:00:00 sqlplus
oracle   65459 65458  0 May16 ?        00:00:00 oracleQPDEV (DESCRIPTION=(LOCAL=YES)(ADDRESS=(PROTOCOL=beq)))
oracle   65518     1  0 Jun08 ?        00:00:00 oracleQPDEV (LOCAL=NO)
oracle   65520     1  0 Jun08 ?        00:00:02 oracleQPDEV (LOCAL=NO)
oracle   65534     1  0 Jun08 ?        00:00:00 oracleQPDEV (LOCAL=NO)

oracle@LINUX201:[~] $ kill -9 64785
oracle@LINUX201:[~] $ sqlplus "/as sysdba"

SQL*Plus: Release 11.2.0.4.0 Production on Mon Jun 13 10:26:25 2016

Copyright (c) 1982, 2013, Oracle.  All rights reserved.

ERROR:
ORA-00020: maximum number of processes (500) exceeded


Enter user-name: ^C

Killing few processes on Linux :

oracle@LINUX201:[~] $ kill -9 65192 65085 64785 64777 64655 64653 64637


oracle@LINUX201:[~] $ ps -ef|grep 65192 65085 64785 64777 64655 64653 64637

.
.
.
.
oracle   50258     1  0 Jun07 ?        00:00:04 oracleQPDEV (LOCAL=NO)
oracle   50264     1  0 Jun07 ?        00:00:03 oracleQPDEV (LOCAL=NO)
oracle   50268     1  0 Jun07 ?        00:00:02 oracleQPDEV (LOCAL=NO)
.
.
.
oracle   64554     1  0 Jun08 ?        00:00:01 oracleQPDEV (LOCAL=NO)
oracle   64633     1  0 Jun08 ?        00:00:03 oracleQPDEV (LOCAL=NO)
oracle   65186     1  0 Jun08 ?        00:00:04 oracleQPDEV (LOCAL=NO)
oracle   65190     1  0 Jun08 ?        00:00:00 oracleQPDEV (LOCAL=NO)
oracle   65202     1  0 Jun08 ?        00:00:00 oracleQPDEV (LOCAL=NO)
oracle   65206     1  0 Jun08 ?        00:00:02 oracleQPDEV (LOCAL=NO)
.
.
.

oracle@LINUX201:[~] $ sqlplus "/as sysdba"

SQL*Plus: Release 11.2.0.4.0 Production on Mon Jun 13 10:30:07 2016

Copyright (c) 1982, 2013, Oracle.  All rights reserved.


Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL> show parameter process;

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
aq_tm_processes                      integer     1
cell_offload_processing              boolean     TRUE
db_writer_processes                  integer     1
gcs_server_processes                 integer     0
global_txn_processes                 integer     1
job_queue_processes                  integer     1000
log_archive_max_processes            integer     4
processes                            integer     500
processor_group_name                 string


Now reset the max processes to a greater value:

SQL> alter system set processes=1200 scope=spfile;

System altered.

SQL>  show parameter process;

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
aq_tm_processes                      integer     1
cell_offload_processing              boolean     TRUE
db_writer_processes                  integer     1
gcs_server_processes                 integer     0
global_txn_processes                 integer     1
job_queue_processes                  integer     1000
log_archive_max_processes            integer     4
processes                            integer     500
processor_group_name                 string
SQL> select name,open_mode from v$database;

NAME      OPEN_MODE
--------- --------------------
QPDEV     READ WRITE

This will need a restart to take affect


SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.

SQL> startup;
ORACLE instance started.

Total System Global Area 3206836224 bytes
Fixed Size                  2257520 bytes
Variable Size            1275071888 bytes
Database Buffers         1912602624 bytes
Redo Buffers               16904192 bytes
Database mounted.
Database opened.

SQL> show parameter process

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
aq_tm_processes                      integer     1
cell_offload_processing              boolean     TRUE
db_writer_processes                  integer     1
gcs_server_processes                 integer     0
global_txn_processes                 integer     1
job_queue_processes                  integer     1000
log_archive_max_processes            integer     4
processes                            integer     1200
processor_group_name                 string

SQL>