Newsletters Archive - 2008

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  Connecting to ASM through the TNS Listener from a Client Desktop — (29-January-2008)

By default, the Oracle Database Configuration Assistant (DBCA) does not 
configure the TNS listener to accept client requests to an ASM instance running 
from a different node. Access will be denied for clients like SQL*Plus, 
Perl DBI:DBD, and JDBC when attempting to connect to an ASM instance from a 
node other than the node running the ASM instance. When the service is created 
for an ASM instance, its status is BLOCKED:

[oracle@linux1 ~]$ lsnrctl status LISTENER_LINUX1 | grep ASM
Service "+ASM" has 1 instance(s).
  Instance "+ASM1", status BLOCKED, has 1 handler(s) for this service...
Service "+ASM_XPT" has 1 instance(s).
  Instance "+ASM1", status BLOCKED, has 1 handler(s) for this service...

This limitation puts restrictions on scripts and other client tools that want 
to monitor and manage an ASM instance from a different node. Getting around 
this restriction however is an easy task that involves manually creating a 
service name for the ASM instance.

The following article presents the steps required to access an ASM instance 
through the TNS listener from a client desktop. The database used in this 
article is a two-node Oracle RAC 10g clustered database where in fact there 
will two ASM instances (one ASM instance for each Oracle instance in the 
cluster). The database version is Oracle 10g Release 2 (10.2.0.3.0) running on 
CentOS 4.5 (or RHEL 4.5):

Connecting to ASM through the TNS Listener from a Client Desktop

----------------------------
Jeffrey M. Hunter
Sr. Database Administrator
jhunter@idevelopment.info
http://www.idevelopment.info
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