Not able to connect to oracle directly

Question

os : AIX ch5dlfp089 1 6 000B4A22D900
oracle : 11.2.0.1.0
Issue : created oracle db using dbca (gui). Db created successfully
When I checked recently using putty to check the db health. I am able to see smon and orcl is running well using
ps -eaf | grep orcl.
How ever when I am trying to connect the db using sqlplus prompt. It is showing idle instance.
$ sqlplus "/ as sysdba"
SQL*Plus: Release 11.2.0.1.0 Production on Mon Oct 18 00:52:08 2010
Copyright (c) 1982, 2009, Oracle. All rights reserved.
Connected to an idle instance.
SQL> exit
oratab entry shows ok
orcl:/home/oracle/app/oracle/product/11.2.0/dbhome_1:
CHECKED BASIC ENV. variables values
$ echo $ORACLE_SID
orcl
$ echo $ORACLE_HOME
/home/oracle/app/oracle/product/11.2.0/dbhome_1/
profile shows as follows
$ cat .profile
PATH=/usr/bin:/etc:/usr/sbin:/usr/ucb:$HOME/bin:/usr/bin/X11:/sbin:.
export PATH
if [ -s "$MAIL" ] # This is at Shell startup. In normal
then echo "$MAILMSG" # operation, the Shell checks
fi # periodically.
ORACLE_SID=orcl
export ORACLE_SID
ORACLE_HOME=/home/oracle/app/oracle/product/11.2.0/dbhome_1/
export ORACLE_HOME
LIBPATH=$ORACLE_HOME/lib:$LIBPATH
export LIBPATH
PATH=$ORACLE_HOME/bin:$PATH
export PATH
However I am able to connect to db using tns
$ sqlplus "sys/Oracle123@orcl as sysdba"
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> EXIT
Question : what could be the reason I am not able to connect the db directly ? without tns ?
Any mistake could have happend or any restriction could have set for this access ?

Answer 1

I already tested that ORCL
$ echo $ORACLE_SID
orcl
$ export ORACLE_SID=ORCL
$ echo $ORACLE_SID
ORCL
$ sqlplus "/ as sysdba"
SQL*Plus: Release 11.2.0.1.0 Production on Mon Oct 18 01:08:03 2010
Copyright (c) 1982, 2009, Oracle. All rights reserved.
Connected to an idle instance.
LISTNER
$ lsnrctl status
LSNRCTL for IBM/AIX RISC System/6000: Version 11.2.0.1.0 - Production on 18-OCT-2010 01:09:00
Copyright (c) 1991, 2009, Oracle. All rights reserved.
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=EXTPROC1521)))
STATUS of the LISTENER
Alias LISTENER
Version TNSLSNR for IBM/AIX RISC System/6000: Version 11.2.0.1.0 - Production
Start Date 14-OCT-2010 00:14:39
Uptime 4 days 0 hr. 54 min. 22 sec
Trace Level off
Security ON: Local OS Authentication
SNMP ON
Listener Parameter File /home/oracle/app/oracle/product/11.2.0/dbhome_1/network/admin/listener.ora
Listener Log File /home/oracle/app/oracle/diag/tnslsnr/ch5dlfp089/listener/alert/log.xml
Listening Endpoints Summary...
(DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=EXTPROC1521)))
(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=ch5dlfp089.in.ibm.com)(PORT=1521)))
Services Summary...
Service "orcl.in.ibm.com" has 1 instance(s).
Instance "orcl", status READY, has 1 handler(s) for this service...
Service "orclXDB.in.ibm.com" has 1 instance(s).
Instance "orcl", status READY, has 1 handler(s) for this service...
The command completed successfully
$
TNS SHOWS
$ tnsping orcl
TNS Ping Utility for IBM/AIX RISC System/6000: Version 11.2.0.1.0 - Production on 18-OCT-2010 01:09:51
Copyright (c) 1997, 2009, Oracle. All rights reserved.
Used parameter files:
/home/oracle/app/oracle/product/11.2.0/dbhome_1/network/admin/sqlnet.ora
Used TNSNAMES adapter to resolve the alias
Attempting to contact (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = ch5dlfp089.in.ibm.com)(PORT = 1521)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = orcl.in.ibm.com)))
OK (30 msec)
$
TNSNAMES ENTRY
$ cat tnsnames.ora
# tnsnames.ora Network Configuration File: /home/oracle/app/oracle/product/11.2.0/dbhome_1/network/admin/tnsnames.ora
# Generated by Oracle configuration tools.
orcl =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = ch5dlfp089.in.ibm.com)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = orcl.in.ibm.com)
)