How to resolve error TNS:listener does not currently know of service requested in connect descriptor

This time we would like to look at one of problem in oracle, especially “ORA-12514: TNS:listener does not currently know of service requested in connect descriptor”.

The vast majority of the time, this error results from an incorrectly specified connect descriptor in the tnsnames.ora file. Let’s look at a very typical example then diagnose and fix it. After that we will dig in to how the listener comes to know of a service name.

For the first we need to analyze why the error occured by starting listener.

[oracle@vmlnx01 admin]$ lsnrctl start
 
LSNRCTL for Linux: Version 10.2.0.4.0 - Production on 16-MAR-2011 18:44:49
 
Copyright (c) 1991, 2007, Oracle.  All rights reserved.
 
Starting /ora00/app/oracle/product/10.2.0/db_1/bin/tnslsnr: please wait...
 
TNSLSNR for Linux: Version 10.2.0.4.0 - Production
Log messages written to /ora00/app/oracle/product/10.2.0/db_1/network/log/listener.log
Listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=vmlnx01.vmdomain)(PORT=1521)))
 
Connecting to (ADDRESS=(PROTOCOL=tcp)(HOST=)(PORT=1521))
STATUS of the LISTENER
------------------------
Alias                     LISTENER
Version                   TNSLSNR for Linux: Version 10.2.0.4.0 - Production
Start Date                16-MAR-2011 18:44:49
Uptime                    0 days 0 hr. 0 min. 0 sec
Trace Level               off
Security                  ON: Local OS Authentication
SNMP                      OFF
Listener Log File         /ora00/app/oracle/product/10.2.0/db_1/network/log/listener.log
Listening Endpoints Summary...
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=vmlnx01.vmdomain)(PORT=1521)))
The listener supports no services
The command completed successfully

It said that The listener supports no services. It means that the listener doesn't have any associates service. So the solution is we need to add a service to listener.ora as example below :

SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (GLOBAL_DBNAME=vlnxora1)
      (ORACLE_HOME = /ora00/app/oracle/product/10.2.0/db_1)
      (SID_NAME = vlnxora1)
    )
  )

LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = vmlnx01.vmdomain)(PORT = 1521))
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC0))
    )
  )

Restart listener by command lsnrctl stop followed by lsnrctl start. Now you can try login using your oracle user e.g : sqlplus scott@vlnxora1

If you get this problem in your oracle client installation, please make sure that your service name is configured correctly. To check that, do the following steps :

1. Edit tnsnames.ora
2. Make sure that service name in connect descriptor is same with oracle database service name.
3. To check oracle database service name, login to your oracle database server and execute the query below : 

   sqlplus / as sysdba
   select value from v$parameter where name='service_names';
   show parameter service_names;

4. To change oracle service name you can use alter

   ALTER SYSTEM SET SERVICE_NAMES='application_a.your.domain','application_b.your.domain' SCOPE=BOTH;

How to troubleshoot ‘cannot restore segment prot after reloc: Permission denied’

The error above occurs because the settings of selinux. To troubleshoot that problem, do the following:

1. Go to System -> Administration -> Security Level and Firewall -> SELinux Tab
2. Change "Enforce" to "Disabled"
3. Alternatively you can edit selinux setting by editing file /etc/selinux/config

How to edit fstab when at "Repair filesystem" prompt

Have you ever got an error in linux that caused by the errors on the filesystem??. If so, you would get "Repair filesystem" prompt appeared.

This post will discuss about how to troubleshoot linux when "Repair filesystem" prompt appears on RHEL 5. Here are the steps :

1. Boot your system with Redhat Linux Disk1
2. Go through the Linux Rescue process and you will get a hash prompt
3. Type the command below
   

   # vi /mnt/sysimage/etc/fstab
   

4. Save using wq

Troubleshoot CD/DVD Rom

Dear Readers, At this time we will discuss thoroughly about the CD/DVD Rom, it's problems, how to treat a CD/DVD Rom etc. Hopefully this discussion will be helpful.

CD/DVD Rom does not read
solution:

• Clean the head of CD/DVD Rom
  I Often get the question, why CD/DVD Rom can not read? when I recently bought 2-3 months ago, the first question I ask is whether it's head ever cleaned??. Head on CD/DVD Rom has the same function as the eyes, if the head/eyes dirty then our vision will dim or obscure, as well as head CD/DVD Rom, a laser beam generated by the head can be blocked by dust which resulted in reading the CD/DVD so it is not smooth. The solution, buy a CD/DVD Rom cleaner, usually equipped with alcohol.
  
• Clean the CD/DVD
  I Often find there is fat or hand printing on the surface of the CD/DVD, this will make CD/DVD Rom be broken, because the head will be forced to read the CD/DVD, hence before the CD/DVD is inserted into the drive, make sure it's clean from dust, fat or other materials. To clean fat or hand printing we can use cd cleaners that are sold in many computer stores.
  

CD/DVD Rom can not be ejected
Ever have a CD/DVD stuck and can not be removed from the drive??, if so grab a paper clip, then while pressing the eject button on CD, press into a small hole located on the CD/DVD rom.

CD/DVD Rom is not detected
The common problems, to fix it, first check whether the indicator light on the CD/DVD Rom is lit, if it does not, it mean that the matter is power, try to replace the power that is connected to a CD/DVD Rom with another power cable, of course, we have to open the computer casing first. If it's lit but CD/DVD Rom still not detected, the next step is to check the IDE cable, it's the flexi size cable that attach the power cable in addition, try to replace it with another IDE cable, usually by using two steps of this, CD/DVD Rom will be detected again, if it's not then it can be hardware damage and we may have to buy a new one.

Fixing error NTLDR is missing

Have you experienced error message "NTLDR is missing Press any key to restart" or "NTLDR is missing Press Ctrl Alt Del to restart" or "Boot: Couldn’t find NTLDR Please insert another disk" ???. This posting will discuss about how to fixing that kind of errors.
NTLDR error messages occur after the POST ( Power On Self Test) is completed or after the process of checking hardware in windows.

Causes of the error message

• PC boot to USB, CD or Hard Drive which does not have a boot sector.
• Windows have corrupted.
• There was an error on boot configuration file.
• Cables IDE/Sata damaged, so the data does not flow perfectly.
• The windows upgrade process is not complete.

Standard Solutions

1. simply restart our PC/Laptop.
2. Check if there is flash disk, CD or other media that is connected to a PC/ lapptop, if any pull it, this is to prevent booting from the media
3. Check the BIOS, whether the first boot is from the Hard Drive that has a boot sector or Windows is installed

If all that solutions don't work, try the following:

1. Insert the Windows CD into the CD/DVD Drive.
2. Restart your PC/Laptop and set the first boot from CD/DVD Drive.
3. Press enter on the message "press anykey to boot from CD".
4. After entering the Setup Menu, press "R" to enter the repair command line.
5. Next will be asked, where the windows system lies??, choice of numbers appears, select the number that contained the windows system, for example: if on drive C then choose number 1
6. Next will be asked the administrator password, type it and enter.
7. Copy the files NTLDR & NTDETECT.com into the system. For example if CD/DVD drive is drive 'D', then the command is
   

   Copy d:\i386\ntldr c:\
   Copy d:\i386\ntdetect.com c:\
   

8. If success, then there will be written "2 files copied".
9. Restart PC and select boot from first hard drive.

How to Troubleshoot "The procedure entry point OCIClientVersion could not be located in the dynamic link library OCI.dll"

Once upon a time, i have been installing xampp that will be connected to oracle database (php connect to oracle) in windows. After installing i have commented the line to enable php_oci8.dll and php_pdo_oci8.dll.
But when i try to start apache, there is error as below :

How to solve this ??
There are somethings that you must check :

1. Stop apache
2. Check that you have set ORACLE_HOME environment variable
3. Remove or rename file oci.dll under c:/xampp/apache/bin/ and under c:/xampp/php/
4. Start apache