ORA-27101: shared memory realm does not exist tips
Oracle Error Tips by Burleson Consulting
Oracle docs note this about ORA-27101:
MOSC offers valuable information regarding ORA-27101. ORA-27101 is often
thrown along with ORA-01034 during database installation. ORA-27101 is
also seen after installation is complete, when attempting to use SQL*Plus.
To resolve this issue with ORA-27101, you should be sure that ORACLE_HOME and
ORACLE_SID are correct, and ORACLE_HOME should not have trailing slash.
Here is the MOSC example to accompany ORA-27101 resolution instructions:
For checking on trailing trash:
$ echo $ORACLE_HOME
$ /app/oracle/817/ << Incorrect
$ echo $ORACLE_HOME
$ /app/oracle/817 << Correct
$ echo $ORACLE_SID
$ ps -ef | grep smon
(Here, ORACLE_SID setting has been altered from ora817 to ORA817.)
Basically, to resolve ORA-27101, Once ORACLE_HOME and ORACLE_SID
are correct, and then attempt to start SQL*Plus.
Choi also offers some great information on ORA-27101 in AllExperts.
I keep receiving ORA-27101 with ORA-01034 after
I tried installing the Oracle XE on Windows XP. Unfortunately, when I
connect to the database, ORA-27101 is thrown instead. Any help?
ORA-27101 may indicate that the system was not
able to find the shared memory realm. So, you could be receiving ORA-27101
because you tried to modify the database parameters such as SGA size. If
this is something that you have done and feel this is why you are encountering
ORA-27101, you can try to bring back the original parameters. Another
cause of ORA-27101 is that the instance pointer, or ORACLE_SID, may be
gone. If this is the case, to resolve ORA-27101 you should first try
looking for ORACLE_SID. There are several different methods depending on
what server you are using:
- For Unix- try using "echo $ORACLE_SID"
- For Windows- right click on My Computer¢properties¢Advance
Tab¢Environment Variable. You can view
here where or not ORACLE_SID is defined.
If you find in either cases that ORACLE_SID
is blank or undefined, this may be the cause of ORA_27101. You can then
set the ORACLE_SID appropriate for the database to resolve ORA-27101.
"After running Oracle 11 flawlessly for quite some time, this error
suddenly arose in my environment this morning. After about 5 hours of
debugging, and know that nothing new had been installed and configured
on my Oracle server, I discovered that this was occurring because my
Windows Event Log was full.
Apparently, if the Windows Event Log is full, then Oracle cannot attach
to the shared memory realm properly during startup and you'll then get
this error when attempting to login as any user.
After cleaning out my various event logs, Oracle is now working properly