Expert: Peter Choi - 12/9/2005

Question
I installed Oracle xe on my pc windows xp, every time when I tried to connect into database, it gave me the following errors:

ORA-01034: Oracle not available,
ORA-27101: shared memory realm does not exist

Please help me.


Answer
Hi Hong,

Causes of ORA-27101

Unable to locate shared memory realm.

So it may be one of this

1. You may have modified your Database Parmaters (SGA Size or some other related parameter).

Action: Restore original parameters that you may have changed (manually or throught the wizard).

2. Your database instance pointer is gone. i.e. ORACLE_SID

Action: Check your environmental variables looking for the ORACLE_SID parameter. On Unix, you can type "echo $ORACLE_SID" and if it returns blank, then it has not been set. On a Windows server, right mouse click (RMC) on My Computer, select properties, select Advance Tab, click on the Environment Variable button. Look throught both sets of lists to see if ORACLE_SID is defined. In both cases if they are blank or not assigned, set it to your Oracle SID assigned to the database (this is assigned at creation time. The default sid for the first database created is ORCL).

Hope this helps!

Peter