Registering Database Service With Listener

Registering DB Service with Listener | Static vs. Dynamic

Client connecting to the remote database

Let it be, user scott is connecting remote database using sqlplus. I have a

deep look here how the connection is established. Let’s see ..

SQL> username/password@net_service_name

SQL> scott/tiger@orcltest

When user scott issues this statement then the user can connect with the

database. Here sqlplus asking TNS to make a connection to “orcltest”

using (userid scott and the password tiger). This is client request

and can be found on CLIENT MACHINE that the file name is

“tnsnames.ora”.

The tnsnames.ora file can be identified

$ORACLE_HOME/network/admin.

Consider tnsnames file has this entry :

Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu


TNS (Transparent Network Substrate) looks tnsnames.ora for an entry

called ORCLTESTDB. This is called as (tns.alias_name or

net_service_name).

Here a request is sent through the normal OS network stack to (PORT = 1521)

on (HOST = linuxserver) using (PROTOCOL = TCP), asking for a connection to

(SERVICE_NAME = orcltest). These entry information’s can be getting from

tnsnames.ora file only.

Ok , What about the listener’s Part here ?

The Listener is separate process that runs on database server side. It

receives incoming client connection requests (who is trying to connect DB

server) and make the connection (Server Process) between the client and

the database instance. The listener is configured with the listener.ora file.

POINTS TO REMEMBER



If the listener goes down, new users would not be able to connect to my

DB server but connected users would be able to work normally.

Static vs. Dynamic Instance Registration : ( LISTENER)

Oracle Provides two methods service registered with listener - They are

STATIC and DYNAMIC

READY - DYNAMIC REGISTRATION

UNKNOWN - STATIC REGISTARTION

INSTANCE Static Registration :

Means listener knows because of SID_LIST entry in the listener.ora :

(SR).

Static is the very basic method to register listener. we can add entries in

$ORACLE_HOME\NETWORK\ADMIN\listener.ora file or netmgr (GUI)

mode.

Database service can be confirmed by following command ,

SQL> show parameter service;

STATIC registration is accomplished by configuring the SID_LIST section of

the listener.ora file. The configuration inside the listener.ora file looks like

below.



$ lsnrctl start

LSNRCTL for Linux: Version 10.2.0.4.0 - Production on 15-MAR-2013 20:58:31

Copyright (c) 1991, 2005, Oracle. All rights reserved.:

Starting /u01/app/oracle/product/10.2.0/db_1/bin/tnslsnr: please wait...

TNSLSNR for Linux: Version 10.2.0.4.0 - Production

Listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=linuxserver)

(PORT=1521)))

Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=linuxserver)

(PORT=1521)))

Listening Endpoints Summary...

(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=linuxserver)(PORT=1521)))

Services Summary...

Service "MYDB.ORCLPROD.COM" has 1 instance(s).



Instance "orclprod", status UNKNOWN, has 1 handler(s) for this service...

Service "myorcltest" has 1 instance(s).

Instance "orcltest", status UNKNOWN, has 1 handler(s) for this service...

The command completed successfully

REGISTRATION STATUS IS UNKNOWN - WHY ?

Status is UNKNOWN. This status of unknown is the indication that this

registration came from the SID_LIST section of listener.ora. Listener do

NOT have any information about the status. Ok. Let’s take a deep look.

Listener status with actual connection request

SQL> conn user1/user1@ORCLTESTDB

Connected.

$ lsnrctl status



(DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=EXTPROC0)))

Services Summary...

Service " MYDB.ORCLPROD.COM " has 1 instance(s).

Instance "orclprod", status UNKNOWN, has 1 handler(s) for this service...

Service "myorcltest" has 1 instance(s).

Instance "orcltest", status UNKNOWN, has 1 handler(s) for this service...

Service "orclprod" has 1 instance(s).

Instance "orclprod", status READY, has 1 handler(s) for this service...

Service "orclprodXDB" has 1 instance(s).




Service "orclprod_XPT" has 1 instance(s).


Service "orcltest" has 1 instance(s).

Instance "orcltest", status READY, has 1 handler(s) for this service...

Service "orcltestXDB" has 1 instance(s).


Service "orcltest_XPT" has 1 instance(s).



We can ignore the services XDB and XTP - Special internal uses for Oracle.

Marked status is unknown because there is no mechanism to guarantee that

the specified UNKNOWN status (Static Registation). If we ask connections to

(MYDB.ORCLPROD.COM, myorcltest) the listener just saying NO databases

named MYDB.ORCLPROD.COM or myorcltest.

The READY instance comes from the database having registered with the

listener (Dynamic Registration).

Dynamic Registration

Dynamic registration is accomplished when the pmon process of the database

instance contacts the listener and requests registration. This occurs at instance

startup, and every 60 seconds ( during life of the instance on port #1521).

Three Initialization parameters that affect service_names .



DB_NAME, DOMAIN_NAME, SERVICE_NAMES

NOTE : pmon background process registers with

listener.

DYNAMIC REGISTRATION STEPS

First completely removing listener.ora , then restarting the listener and

confirm no static registration is running.

linux> $ rm –rf listener.ora

linux> $ ls -ld *.ora

-rw-r--r-- 1 oracle oinstall 565 Mar 16 04:41 tnsnames.ora

Stoping Listener

linux> $ lsnrctl stop

LSNRCTL for Linux: Version 10.2.0.4.0 - Production on 18-MAR-2013

Copyright (c) 1991, 2005, Oracle. All rights reserved.

Connecting to (ADDRESS=(PROTOCOL=tcp)(HOST=)(PORT=1521))


Starting Listener

$ lsnrctl start



Starting /u01/app/oracle/product/10.2.0/db_1/bin/tnslsnr: please wait...

TNSLSNR for Linux: Version 10.2.0.4.0 - Production






The listener supports no services


* Note: The listener started with all default values and support no services.*

Example : I Changes In orcltest database

SQL> show user;

USER is "SYS"

SQL> alter system set service_names='' scope=spfile;

System altered.

SQL> alter system set db_domain='' scope=spfile;

System altered.

SQL> startup force;

ORACLE instance started.

Database opened.

SQL> show parameter db_domain;

NAME TYPE VALUE

db_domain string -----------

SQL> show parameter service_names;

NAME TYPE VALUE

service_names string ------------



SQL> alter system register;

System altered.

SQL> select * from global_name;

GLOBAL_NAME

ORCLTEST.REGRESS.RDBMS.DEV.US.ORACLE.COM

Checking lsnrctl status for Dynamic Registration

$ lsnrctl status






Services Summary...
















POINTS TO NOTE :

Service names for instance orcltest : (orcltest , orcltest_XPT , orcltestXDB).

Service names for instance orclprod : (orclprod , orclprod_XPT , orclprodXDB).

Service_names associated with the appropriate instance “orcltest/orclprod”

and derived their name from the initialization parameter “db_name”.

Example : II Changes In orcltest database

SQL> show user;

USER is "SYS"

SQL> alter system set service_names='mydb' scope=spfile;

System altered.

SQL> startup force;


Database mounted

Database opened.

SQL> show parameter db_name

NAME TYPE VALUE

db_name string orcltest




NAME TYPE VALUE

service_names string mydb ( see lsnrctl status o/p)


NAME TYPE VALUE

db_domain string


System altered.


$ lsnrctl status






Services Summary...

Service "mydb" has 1 instance(s).

















Service names for instance orcltest : (orcltest , orcltest_XPT , orcltestXDB).

Service names for instance orclprod : (orclprod , orclprod_XPT , orclprodXDB).

Additionaly new service_name “mydb” is derived from “service_names”. Example : III S etting db_domain in orcltest database

SQL> show user;

USER is "SYS"

SQL> alter system set db_domain='orcltest.com' scope=spfile;

System altered.

SQL> startup force;


Database mounted

Database opened.

SQL> show parameter db_name



NAME TYPE VALUE

db_name string orcltest


NAME TYPE VALUE

service_names string mydb


NAME TYPE VALUE

db_domain string ORCLTEST.COM


System altered.


$ lsnrctl status






Services Summary...

Service "mydb.ORCLTEST.com" has 1 instance(s).




Service "orcltest.ORCLTEST.com" has 1 instance(s).


Service "orcltestXDB.ORCLTEST.com" has 1 instance(s).


Service "orcltest_XPT.ORCLTEST.com" has 1 instance(s).



All service names are derived from db_name (orcltest.ORCLTEST.com,

orcltestXDB.ORCLTEST.com, orcltest_XPT.ORCLTEST.com ).

This (mydb.ORCLTEST.com) is derived from service_names and additionly

append the value of db_domain.

POINTS TO NOTE

IN DYNAMIC SERVICE REGISTRATION the status is always (READY), because

the listener knows the instance is ready because the instance itself told the

listener it was ready.

Checking lsnrctl service for Dynamic Registration

$ lsnrctl services



Services Summary...

Service "mydb.ORCLTEST.com" has 1 instance(s).


Handler(s):



"DEDICATED" established:0 refused:0 state:ready

LOCAL SERVER

Service "orcltest.ORCLTEST.com" has 1 instance(s).


Handler(s):


LOCAL SERVER

Service "orcltestXDB.ORCLTEST.com" has 1 instance(s).


Handler(s):

"D000" established:0 refused:0 current:0 max:1022 state:ready

DISPATCHER <machine: linuxserver, pid: 5216>

(ADDRESS=(PROTOCOL=tcp)(HOST=linuxserver)(PORT=32783))

Service "orcltest_XPT.ORCLTEST.com" has 1 instance(s).


Handler(s):


LOCAL SERVER The command completed successfully

POINTS TO REMEMBER for ( DYNAMIC REGISTRATION )

The listener is quite capable of running without a listner.ora file .

DR Service doesn’t require any configuration in the listener.ora file.

The registration is performed by the PMON process (background process).

Pmon registers the DB instance info to the listener and during service

registration Pmon provides following information



Name of the associated Instance.

Current load and maximum load on instance

Names of DB services provided by database.

Information about dedicated servers and dispatchers i.e.

Depends on database server mode i.e. DEDICATED/SHARED server mode.

PMON process wakes up at every 60 seconds and provide information to the

listener. If any problem arises and Pmon process fails (so not possible to

register information with listener) in this case we can force.

Using SQL> alter system register;

Command help to find current listener ( If we configure multiple listeners) ,

Using LSNRCTL> show current listener;

If we try to start up databases remotely should have a static entry

(listener.ora entry) otherwise will not be able to connect to the database.

Oracle netmgr is a utility used for configuring SQL*Net. To enable netmgr,

for UNIX/LINUX systems linux> $ netmgr.

STATUS : Static and Dynamic when using static

Registration

Even though the database is statically registered, the listener uses the Dynamic

Registration information before using static service registration information.

Let’s check with new database named “SBI”



TNS entry for SBI DATABASE

SBIDB =

(DESCRIPTION =

(ADDRESS = (PROTOCOL = TCP)(HOST = linuxserver)(PORT = 1521))

(CONNECT_DATA =

(SERVER = DEDICATED)

(SERVICE_NAME = sbi)

)

)

LISTENER entry for SBI DATABASE

SID_LIST_LISTENER =

(SID_LIST =

(SID_DESC =

(SID_NAME = sbi)

(ORACLE_HOME = /u01/app/oracle/product/10.2.0/db_1)

(GLOBAL_DBNAME =SBI)

)

)

POINTS TO NOTE

lsnrctl> status/services both having UNKNOWN and READY status.

Checking lsnrctl Status

Service "SBI" has 2 instance(s).



It is coming from Service Summary because of listener have entry with

this name GLOBAL_DBNAME.

$ lsnrctl status




(PORT=1521)))



(DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=EXTPROC0)))

Services Summary...


Instance "sbi", status UNKNOWN, has 1 handler(s) for this service...

Instance "sbinst", status READY, has 1 handler(s) for this service...

Service "sbi_XPT" has 1 instance(s).



Instance “SBI”, status UNKNOWN

Instance “sbinst”, status READY

Even database is statically registered, it still registers dynamically with listener.

In the case of both STATIC and DYNAMIC registration, the listener uses the

dynamic registration information before using static service registration info.

Checking lsnrctl Status



$ lsnrctl services




(PORT=1521)))

Services Summary...


Instance "sbi", status UNKNOWN, has 1 handler(s) for this service...

Handler(s):

"DEDICATED" established:0 refused:0

LOCAL SERVER


Handler(s):


LOCAL SERVER

Service "sbi_XPT" has 1 instance(s).


Handler(s):


LOCAL SERVER



Registering Database Service With Listener

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