ORA-00020 error on ASM instance
Tue Oct
09 22:01:09 2012
WARNING:
ASM communication error:
op 17 state 0x40 (20)
ERROR:
slave communication error with ASM
WARNING:
ASM communication error: op 18 state 0x40 (20)
ERROR:
slave communication error with ASM
NOTE:
Deferred communication with ASM instance
Errors
in file /u01/app/oracle/diag/rdbms/abcuat/abcuat1/trace/abcuat1_mmon_6564.trc:
ORA-00020: maximum number of processes (100)
exceeded
ORA-00020:
maximum number of processes (100) exceeded
NOTE:
deferred map free for map id 85
ORA-01565: Unable to open Spfile
+DATA_EUX/abcuat/spfileabcuat.ora.
System State dumped to trace file
/u01/app/oracle/diag/rdbms/abcuat/abcuat1/trace/abcuat1_mmon_6564.trc ß5.5G .trc file
Tue Oct
09 22:01:11 2012
WARNING:
ASM communication error:
op 18 state 0x40 (20)
ERROR:
slave communication error with ASM
NOTE:
Deferred communication with ASM instance
It is believed that ASM instance is not enough to serve the Oracle instances. The original processes limit is only 100. I want to increase it to 200. The below steps are performed to fix the problem:
- Login as root
- run: su grid
- run: sqlplus / as sysdba (some page may say using: sqlplus / as sysasm)
[grid@xdb01 root]$ sqlplus / as sysdba
SQL*Plus: Release 11.2.0.2.0 Production on Fri Nov 23 20:47:24 2012
Copyright (c) 1982, 2010, Oracle. All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.2.0 - 64bit Production
With the Real Application Clusters and Automatic Storage Management options
SQL> show parameter processes
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
processes integer 100
SQL> select count(*) from v$process;
(currently, 76 processes are used.)
COUNT(*)
----------
76
SQL> alter system set processes=200 scope=spfile;
System altered.
(The below step is for shutdown the ASM. Since I use Grid, instead shutdown and startup the ASM instance, I reboot each node.)
SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup
ORACLE instance started.
SQL> show parameter processes
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
processes integer 200
select name, type , value from V$SPPARAMETER where name = 'processes';
After reboot of node 2, all ASM instance are running using 200 processes.
During reboot of node 2, node 1 has 176 processes.
I have recheck the usage of processes:
SQL> select count(*) from v$process;
COUNT(*)
----------
93
SQL> select count(*) from v$process;
COUNT(*)
----------
125
To have a more safety margin, I will increase the limit further.
In the meanwhile, it is worth to double check if SESSIONS is of appropriate limit. Otherwise, we will receive ORA-00018 error.
SQL> show parameter sessions
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
sessions integer 336
SQL> select count(*) from v$session;
COUNT(*)
----------
63
We may refer to this Oracle document ( (1.1 *
PROCESSES) + 5) and forum for a rule-of-thumb on how many sessions shall be allocated.Reference: http://www.shutdownabort.com/errors/ORA-00020.php
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