Re: ORA-27101 "Shared Memory Realm Does Not Exist"

Rick,

Are you trying for two seperate versions of Oracle on the box, or did you remove the 8.1.6 to install 9i? If you did the latter, I'm afraid your uninstall did not go properly and your service isn't pointing to the right place. Oradim is the "supported" method for removing (renaming?) an Oracle instance, but here's some tips I got when I was new to the NT/2000 world from "Novice DBA". I've sent this before, but you should take a look at your registry settings, they're probably the key to your problem and this document will help you know what to look for:

Database Installation involves a set of procedures which need to be followed
in order to have a proper working installation. If we follow these procedures the Installation will be fine and usually problems related to improper installation do not arise. But it is not always possible to get a proper installation for the first time. This document is a troubleshooting guide which would help to clear off the mess created by an improper installation in a WindowsNT system.

First we need to know that During installation Oracle writes into certain directories (which we would have specified during installation) and also into the WindowsNT registry. WindowsNT registry is a repository of information about all the installed products and configurations on that system. When we are installing Oracle a directory is created in the registry
which is name oracle which is present in the HKEY_LOCAL_MACHINE/SOFTWARE/

In the case of an improper installation the problems faced are
· We may not be able to uninstall the incomplete installation
· We may succeed in uninstalling the incomplete installation but yet face
problems with WindowsNT Services.
· Every time we log into WindowsNT we may get an error 'at least one system
service failed to start' which may be an Oracle service from the earlier installation.
· We may get an error while creating a database 'the database with the name
you specified already exists please chose another name' which again may be attributed to an improper un-installation.(I am not pretty comfortable with
the Oracle's Un-installation utility because I feel it does not uninstall everything)

Keeping the above points in mind it would be better if we know where exactly
to look in case we are faced with such problems. When oracle is installed it
makes entries in the following places
1. The first and the foremost- the directory in which we install the Oracle database (say D:\Ora8i)
2. The second is the inventory it maintains in the directory c:\program files\oracle
3. The third HKEY_LOCAL_MACHINE/SOFTWARE/ORACLE in the registry 4. The other place is HKEY_LOCAL_MACHINE/SYSTEM . Inside this entry there are three nodes controlset1,controlset2 and currentcontrolset. These nodes in turn have 4 nodes out of which 2 are important to us. They are Enum and Services. The Enum node has got two nodes out of which the 'root' node is of
great interest to us because it stores details about all the services that are running on a WindowsNT system. The other node of interest from the controlsets is Services. The services node has got a list of services running on a WindowsNT system.

In case we need to clean up the system after an incomplete installation we can follow the following steps
Delete the home directory where Oracle is installed Delete the folder C:\program files\oracle Note:- This clears off information
about any other Oracle utility installed on that system. Delete the registry entry HKEY_LOCAL_MACHINE/SOFTWARE/ORACLE Warning:- This clears off information about any other Oracle utility installed on that system and you may not be able to run those programs again. Delete the Oracle Related services from
HKEY_LOCAL_MACHINE/SYSTEM/CONTROLSETx/ENUM/ROOT/ . They will be named with a
prefix LEGACY_ORACLE... Note:- You will have to use regedt32.exe to invoke registry editor and not regedit. You will have to use the security menu and give permissions to yourself before deleting these entries. Else it will not
work . It is to be noted that there are three control sets and all the three
(in reality any 2) need to be cleared off these un-necessary entries. Delete the Oracle Related services from
HKEY_LOCAL_MACHINE/SYSTEM/CONTROLSETx/SERVICES . They will have a prefix 'Oracle'.

Hope this helps.

David A. Barbour
Oracle DBA, OCP
AISD
512-414-1002

                                                                                                                   
                    Rick_Cale_at_team                                                                                 
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                    root_at_fatcity.c       Subject:     ORA-27101 "Shared Memory Realm Does Not Exist"               
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                    04/29/2002                                                                                     
                    03:43 PM                                                                                       
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I just installed Oracle 9i on a WinNT 4 server. It already had 8.1.6. I installed Oracle 9 into a different home. The service/instance starts. When I try to connect via sqlplus / to create a database I get ORA-27101 "Shared Memory Realm Does Not Exist" . I have the oracle_sid set correctly. Any ideas as I have tried all I know but still get the same error.

Thanks
Rick

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  INET: DBarbour_at_austin.isd.tenet.edu

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