- 08 Nov, 2021
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ORA-27101: shared memory realm does not exist
ORA-27101: shared memory realm does not exist
Cause: Unable to locate shared memory realm
Action: Verify that the realm is accessible
There may be 2 scenarios, which may lead you to encounter ORA-27101
1) Invalid ORACLE_HOME and ORACLE_SID
2) Database is down
[oracle@192 ~]$ sqlplus scott/tiger SQL*Plus: Release 10.2.0.1.0 - Production on Wed May 22 16:48:05 2013 Copyright (c) 1982, 2005, Oracle. All rights reserved. ERROR: ORA-01034: ORACLE not available ORA-27101: shared memory realm does not exist Linux Error: 2: No such file or directory
Scenario 1: Invalid ORACLE_HOME and ORACLE_SID:
ORA-27101 is usually due to the invalid ORACLE_HOME and ORACLE_SID parameters at OS level. You should investigate that ORACLE_HOME and ORACLE_SID are set correctly, and ORACLE_HOME should be without trailing slash.
[oracle@192 ~]$ echo $ORACLE_HOME /data/app/oracle/product/10.2.0/db_1 [oracle@192 ~]$ echo $ORACLE_SID testdb
In our case ORACLE_SID was not correct, we need to export ORACLE_SID to the valid one which is ora19c
[oracle@192 ~]$ export ORACLE_SID=ora10g [oracle@192 ~]$ sqlplus scott/tiger SQL*Plus: Release 10.2.0.1.0 - Production on Wed May 22 16:52:11 2013 Copyright (c) 1982, 2005, Oracle. All rights reserved. Connected to: Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production With the Partitioning, OLAP and Data Mining options
Scenario 2: Database is down:
You may also face it when the database is down, to solve ORA-27101 you may have to start the database only
[oracle@192 ~]$ sqlplus sys/sys as sysdba SQL*Plus: Release 10.2.0.1.0 - Production on Wed May 22 17:07:38 2013 Copyright (c) 1982, 2005, Oracle. All rights reserved. Connected to an idle instance. SQL> startup ORACLE instance started. Total System Global Area 1224736768 bytes Fixed Size 1219112 bytes Variable Size 167773656 bytes Database Buffers 1040187392 bytes Redo Buffers 15556608 bytes Database mounted. Database opened.