Database link not working on client

Question

All,
Platform : Linux
I have created a db link called "TEST_TO_MART " on 11.2.0.1 database which is pointing to another 11.2.0.1 database . Both are resides on same server. I'm getting following error when I'm trying to test.
SQL> sho user
USER is "TEST_APP"
SQL> select * from dual@TEST_TO_MART;
select * from dual@TEST_TO_MART
ERROR at line 1:
ORA-01034: ORACLE not available
ORA-02063: preceding line from TEST_TO_MART
Process ID: 3466
Session ID: 360 Serial number: 16949Target database is up and able to connect without any issues.
Can you guys suggest me what is the problem?
Thanks.

Answer 1

Sorry.  My error and situation seemed so close to this unsolved issue from a year ago, that I didn't copy and paste the details initially.  Here goes:
oracle@linux99 ~]$ sqlplus
SQL*Plus: Release 11.2.0.3.0 Production on Mon Aug 12 22:56:33 2013
Copyright (c) 1982, 2011, Oracle.  All rights reserved.
Enter user-name: test_dblink_20130812
Enter password:
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> DROP DATABASE LINK "TEST_NOW.MDBT.XXX.COM";
Database link dropped.
SQL> CREATE DATABASE LINK "TEST_NOW.MDBT.XXX.COM"
CONNECT TO APP_UHYDRAST_RW
IDENTIFIED BY XXXXXXXX
USING 'mdbt';  2    3    4
Database link created.
SQL> select * from dual@TEST_NOW.MDBT.XXX.COM;
select * from dual@TEST_NOW.MDBT.XXX.COM
ERROR at line 1:
ORA-01034: ORACLE not available
ORA-02063: preceding line from TEST_NOW.MDBT.XXX.COM
Process ID: 6638
Session ID: 544 Serial number: 1753
In listener.ora, we have this (some other DB's are in lower case):
(SID_DESC =
      (SID_NAME = MDBT)
      (ORACLE_HOME = /ora5/app/oracle/product/11.2.0)
      (GLOBAL_DBNAME = MDBT)
and, in tnsnames.ora we have this:
LISTENER_MDBT =
  (ADDRESS = (PROTOCOL = TCP)(HOST = linux99.XXX.com)(PORT = 1522))
MDBT =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = tcp)(HOST = linux99)(PORT = 1522))
    (CONNECT_DATA =
      (SERVICE_NAME = mdbt.XXX.com)
      (SERVICE_NAME = mdbt)
      (SID = MDBT)