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RE: ORA-27123: unable to attach to shared memory segment

Admin — Thu, 10 Jun 2010 12:59:12 GMT

$ sqlplus testusr/password@testdb

SQL*Plus: Release 10.2.0.2.0 - Production on Tue Jan 27 20:53:44 2009

Copyright (c) 1982, 2005, Oracle. All Rights Reserved.

ERROR:
ORA-01034: ORACLE not available
ORA-27123: unable to attach to shared memory segment
SVR4 Error: 13: Permission denied

As per Oracle Error Messages:

Error: ORA-27123: unable to attach to shared memory segment
Cause: shmat() call failed
Action: check permissions on segment, contact Oracle support

Check the oracle executable file permission.

$ cd $ORACLE_HOME/bin
$ ls -l oracle
-rwxrwxr-x 1 oracle dba 119582976 Feb 3 2008 oracle

Here the oracle file permission has -rwxrwxr-x i.e. 775, but this file must have the permission -rwsr-s- -x i.e. 6751

Change the permissions for oracle file.

$ cd $ORACLE_HOME/bin
$ chmod 6751 oracle
$ ls -l oracle
-rwsr-s--x 1 oracle dba 119582976 Feb 3 2008 oracle

After changing the permissions on oracle executable file, all the users are now able to connect to the database without any errors.

ORA-27123: unable to attach to shared memory segment

Admin — Thu, 23 Apr 2009 10:24:22 GMT

Hi,

I am getting the following error message when using sqlplus to login to oracle. I am logged in as my own unix account and not oracle.

gguser@prodhost:/u01/home/gguser > sqlplus ggadmin

SQL*Plus: Release 9.2.0.4.0 - Production on Wed Apr 18 13:23:00 2009

Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved.

Enter password:
ERROR:
ORA-01034: ORACLE not available
ORA-27123: unable to attach to shared memory segment
Error: 13: Permission denied

Here is the solution to this error message:

# cd $ORACLE_HOME/bin

# ls -ltr oracle

-rwxr-xrwx 1 oracle dba 74053740 Sep 04 2003 oracle

The file permissions for "oracle" executable should be "-rwsr-s--x", so that others can access the oracle environment from the same host.

You need to shutdown the oracle database and then issue the command:

cd $ORACLE_HOME/bin

chmod 6751 oracle
ls -lr oracle

rwsr-s--x 1 oracle dba 74053740 Sep 04 2003 oracle

After you do this, startup the oracle database and then try to connect . This should have resolved the issue.

Hope this helps.