Creating RAC Standby DatabaseConfiguration Details:
• Primary Host Names are
RAC_PRIM01 and
RAC_PRIM02• Standby Host Names are
RAC_STDBY01 and
RAC_STDBY02 • The primary database is
RAC_PRIM • Virtual Names are
RAC_PRIM01-vip,
RAC_PRIM02-vip,
RAC_STDBY01-vip and
RAC_STDBY02-vip • Both the primary and standby databases use ASM for storage
• The following ASM disk groups are being used +DATA (for data) and +FRA for Recovery/Flashback
• The standby database will be referred to as
RAC_STDBY• Oracle Managed Files will be used.
• ORACLE_BASE is set to /u01/app/oracle
1. Configure Primary and Standby sites
For Better and Simpler configuration of Data Guard, it is recommended that the Primary and Standby machines have exactly the same structure, i.e.
• ORACLE_HOME points to the same mount point on both sites.
• ORACLE_BASE/admin points to the same mount point on both sites.
• ASM Disk Groups are the same on both sites
2. Install Oracle Software on each site.
• Oracle Clusterware
• Oracle database executables for use by ASM
• Oracle database executables for use by the RDBMS
3. Server Names / VIPs
The Oracle Real Application Clusters 11g virtual server names and IP addresses are used and maintained by Oracle Cluster Ready Services (CRS).
Note: Both short and fully qualified names will exist.
Server Name/Alias/Host Entry Purpose
RAC_PRIM01.local Public Host Name (PRIMARY Node 1)
RAC_PRIM02.local Public Host Name (PRIMARY Node 2)
RAC_STDBY01.local Public Host Name (STANDBY Node 1)
RAC_STDBY02.local Public Host Name (STANDBY Node 2)
RAC_PRIM01-vip.local Public Virtual Name (PRIMARY Node 1)
RAC_PRIM02-vip.local Public Virtual Name (PRIMARY Node 2)
RAC_STDBY01-vip.local Public Virtual Name (STANDBY Node 1)
RAC_STDBY02-vip.local Public Virtual Name (STANDBY Node 2)
4. Configure Oracle Networking
4.1 Configure Listener on Each Site
Each site will have a listener defined which will be running from the ASM Oracle Home. The following listeners have been defined in this example configuration.
Primary Role
Listener_RAC_PRIM01
Listener_RAC_PRIM02
Listener_RAC_STDBY01
Listener_RAC_STDBY02
4.2 Static Registration
Oracle must be able to access all instances of both databases whether they are in an open, mounted or closed state. This means that these must be statically registered with the listener.
These entries will have a special name which will be used to facilitate the use of the Data Guard Broker, discussed later.
4.3 Sample Listener.ora
LISTENER_RAC_STDBY01 =
(DESCRIPTION_LIST =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = RAC_STDBY01-vip)(PORT = 1521)
(IP = FIRST))
)
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = RAC_STDBY01)(PORT = 1521)
(IP = FIRST))
)
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC))
)
)
)
SID_LIST_LISTENER_RAC_STDBY01 =
(SID_LIST =
(SID_DESC =
(GLOBAL_DBNAME=RAC_STDBY_dgmgrl.local)
(SID_NAME = RAC_STDBY1)
(ORACLE_HOME = $ORACLE_HOME)
)
)
4.4 Configure TNS entries on each site.
In order to make things simpler the same network service names will be generated on each site. These service names will be called:
Alias Comments
RAC_PRIM1_DGMGRL.local Points to the RAC_PRIM instance on RAC_PRIM01 using the service name RAC_PRIM_DGMGRL.local. This can be used for creating the standby database.
RAC_PRIM1.local Points to the RAC_PRIM instance on RAC_PRIM01. using the service name RAC_PRIM.local
RAC_PRIM2.local Points to the RAC_PRIM instance on RAC_PRIM02 using the service name RAC_PRIM.local
RAC_PRIM.local Points to the RAC_PRIM database i.e. Contains all database instances.
RAC_STDBY1_DGMGRL.local Points to the RAC_STDBY instance on RAC_STDBY01 using the service name RAC_STDBY1_DGMGRL ** This will be used for the database duplication.
RAC_STDBY1.local Points to the RAC_STDBY instance on RAC_STDBY01 using the service name RAC_STDBY.local
RAC_STDBY2.local Points to the RAC_STDBY instance on RAC_STDBY02 using the service name RAC_STDBY.local
RAC_STDBY.local Points to the RAC_STDBY database i.e. Contains all the database instances
listener_DB_UNIQUE_NAME.local This will be a tns alias entry consisting of two address lines. The first address line will be the address of the listener on Node1 and the second will be the address of the listener on Node 2. Placing both of the above listeners in the address list will ensure that the database automatically registers with both nodes. There must be two sets of entries. One for the standby nodes call listener_RAC_STDBY and one for the primary nodes called listener_RAC_PRIM
Sample tnsnames.ora (RAC_PRIM01)
RAC_PRIM1_DGMGRL.local =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = RAC_PRIM01-vip)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = RAC_PRIM_DGMGRL.local)
)
)
RAC_PRIM1.local =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = RAC_PRIM01-vip)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = RAC_PRIM.local)
(INSTANCE_NAME = RAC_PRIM1)
)
)
RAC_PRIM2.local =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = RAC_PRIM02-vip)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = RAC_PRIM.local)
(INSTANCE_NAME = RAC_PRIM2)
)
)
RAC_PRIM.local =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = RAC_PRIM01-vip)(PORT = 1521))
(ADDRESS = (PROTOCOL = TCP)(HOST = RAC_PRIM02-vip)(PORT = 1521))
(LOAD_BALANCE = yes)
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = RAC_PRIM.local)
)
)
RAC_STDBY1_DGMGRL.local =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = RAC_STDBY01-vip)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = RAC_STDBY_DGMGRL.local)
)
)
RAC_STDBY2.local=
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = RAC_STDBY02-vip)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = RAC_STDBY.local)
(INSTANCE_NAME=RAC_STDBY2)
)
)
RAC_STDBY1.local=
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = RAC_STDBY01-vip)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = RAC_STDBY.local)
(INSTANCE_NAME=RAC_STDBY1)
)
)
RAC_STDBY.local=
(DESCRIPTION =
(ADDRESS_LIST=
(ADDRESS = (PROTOCOL = TCP)(HOST = RAC_STDBY01-vip)(PORT = 1521))
(ADDRESS = (PROTOCOL = TCP)(HOST = RAC_STDBY02-vip)(PORT = 1521)))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = RAC_STDBY.local)
)
)
LISTENERS_RAC_PRIM.local=
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = RAC_PRIM01-vip)(PORT = 1521))
(ADDRESS = (PROTOCOL = TCP)(HOST = RAC_PRIM02-vip)(PORT = 1521))
)
4.5 Configure ASM on each Site
Certain initialisation parameters are only applicable when a database is running in either a standby or primary database role. Defining ALL of the parameters on BOTH sites will ensure that, if the roles are switched (Primary becomes Standby and Standby becomes the new Primary), then no further configuration will be necessary.
Some of the parameters will however be node-specific; therefore there will be one set of parameters for the Primary site nodes and one for the Standby site nodes.
4.6 Primary Site Preparation
The following initialisation parameters should be set on the primary site prior to duplication. Whilst they are only applicable to the primary site, they will be equally configured on the standby site.
Dg_broker_config_file1 Point this to a file within the ASM disk group – Note File need not exist.
Dg_broker_config_file2 Point this to a file within the ASM disk group – Note File need not exist.
db_block_checksum To enable datablock integrity checking (OPTIONAL)
db_block_checking To enable datablock consistency checking (OPTIONAL)
As long as performance implications allow and do not violate existing SLAs it should be mandatory to have db_block_checksum and db_block_checking enabled.
Additionally, the following must also be configured:
Archive Log Mode
The primary database must be placed into archive log mode.
Forced Logging
The standby database is kept up to date by applying transactions on the standby site, which have been recorded in the online redo logs. In some environments that have not previously utilized Data Guard, the NOLOGGING option may have been utilized to enhance database performance. Usage of this feature in a Data Guard protected environment is strongly undesirable.
From Oracle version 9.2, Oracle introduced a method to prevent NOLOGGING transactions from occurring. This is known as forced logging mode of the database. To enable forced logging, issue the following command on the primary database:
alter database force logging;
Password File
The primary database must be configured to use an external password file. This is generally done at the time of installation. If not, then a password file can be created using the following command:
orapwd file=$ORACLE_HOME/dbs/orapwRAC_PRIM1 password=mypasswd
Before issuing the command ensure that the ORACLE_SID is set to the appropriate instance – in this case RAC_PRIM1.
Repeat this for each node of the cluster.
Also ensure that the initialisation parameter remote_login_passwordfile is set to ‘exclusive’.
As with Oracle11.1 the Orale Net sessions for Redo Transport can alternatively be auhenticated through SSL (see also section 6.2.1 in the Data Guard Concepts manual).
Standby Site Preparation
Initialization Parameter File :
As part of the duplication process a temporary initialisation file will be used. For the purposes of this document this file will be called /tmp/initRAC_PRIM.ora have one line:
db_name=RAC_PRIM
Password File
The standby database must be configured to use a password file. This must be created by copying the password file from the primary site to the standby site and renaming it to reflect the standby instances.
Repeat this for each node of the cluster.
Additionally ensure that the initialisation parameter remote_login_passwordfile is set to xclusive.
Create Audit File Destination
Create a directory on each node of the standby system to hold audit files.
mkdir /u01/app/oracle/admin/RAC_STDBY/adump
Start Standby Instance
Now that everything is in place the standby instance needs to be started ready for duplication to commence:
export ORACLE_SID=RAC_STDBY1
sqlplus / as sysdba
startup nomount pfile=’/tmp/initRAC_PRIM.ora’
Test Connection
From the primary database test the connection to the standby database using the command:
sqlplus sys/mypasswd@RAC_STDBY_dgmgrl as sysdba
This should successfully connect.
Duplicate the Primary database
The standby database is created from the primary database. In order to achieve this, up to Oracle10g a backup of the primary database needs to be made and transferred to the standby and restored. Oracle RMAN 11g simplifies this process by providing a new method which allows an ‘on the fly’-duplicate to take place. This will be the method used here (the pre-11g method is described in the Appendicies).
From the primary database invoke RMAN using the following command:
export ORACLE_SID=RAC_PRIM1
rman target / auxiliary sys/mypasswd@RAC_STDBY1_dgmgrl
NOTE: If RMAN returns the error “rman: can’t open target” then ensure that ‘ORACLE_HOME/bin’ appears first in the PATH because there exists a Linux utility also named RMAN.
Next, issue the following duplicate command:
duplicate target database for standby from active database
spfile
set db_unique_name=’RAC_STDBY’
set control_files=’+DATA/RAC_STDBY/controlfile/control01.dbf’
set instance_number=’1’
set audit_file_dest=’/u01/app/oracle/admin/RAC_STDBY/adump’
set remote_listener=’LISTENERS_RAC_STDBY’
nofilenamecheck;
Create an SPFILE for the Standby Database
By default the RMAN duplicate command will have created an spfile for the instance located in $ORACLE_HOME/dbs.
This file will contain entries that refer to the instance names on the primary database. As part of this creation process the database name is being changed to reflect the DB_UNIQUE_NAME for the standby database, and as such the spfile created is essentially worthless. A new spfile will now be created using the contents of the primary database’s spfile.
Get location of the Control File
Before starting this process, note down the value of the control_files parameter from the currently running standby database
Create a text initialization pfile
The first stage in the process requires that the primary databases initialisation parameters be dumped to a text file:
set ORACLE_SID=RAC_PRIM1
sqlplus “/ as sysdba”
create pfile=’/tmp/initRAC_STDBY.ora’ from spfile;
Copy the created file ‘/tmp/initRAC_STDBY.ora’ to the standby server.
Edit the init.ora
On the standby server, edit the /tmp/initRAC_STDBY.ora file:
NOTE: Change every occurrence of RAC_PRIM with RAC_STDBY with the exception of the parameter DB_NAME which must NOT change.
Set the control_files parameter to reflect the value obtained in 4.3.8.1 above. This will most likely be +DATA/RAC_STDBY/controlfile/control01.dbf.
Save the changes.
Create SPFILE
Having created the textual initialisation file it now needs to be converted to a spfile and stored within ASM by issuing:
export ORACLE_SID=RAC_STDBY1
sqlplus “/ as sysdba”
create spfile=’+DATA/RAC_STDBY/spfileRAC_STDBY.ora’ from pfile= ’/tmp/initRAC_STDBY.ora’
Create Pointer File
With the spfile now being in ASM, the RDBMS instances need to be told where to find it.
Create a file in the $ORACLE_HOME/dbs directory of standby node 1 (RAC_STDBY01 ) called initRAC_STDBY1.ora . This file will contain one line:
spfile=’+DATA/RAC_STDBY/spfileRAC_STDBY.ora’
Create a file in the $ORACLE_HOME/dbs directory of standby node 2 (RAC_STDBY02) called initRAC_STDBY2.ora . This file will also contain one line:
spfile=’ +DATA/RAC_STDBY/spfileRAC_STDBY.ora’
Additionally remove the RMAN created spfile from $ORACLE_HOME/dbs located on standby node 1 (RAC_STDBY01 )
Create secondary control files
When the RMAN duplicate completed, it created a standby database with only one control file. This is not good practice, so the next step in the process is to create extra control files.
This is a two-stage process:
1. Shutdown and startup the database using nomount :
shutdown immediate;
startup nomount;
2. Change the value of the control_files parameter to ‘+DATA’,’ +FRA’
alter system set control_files=‘+DATA’,’ +FRA’ scope=spfile;
3. Shutdown and startup the database again :
shutdown immediate;
startup nomount;
3. Use RMAN to duplicate the control file already present:
export ORACLE_SID=RAC_STDBY1
rman target /
restore controlfile from ‘+DATA/RAC_STDBY/controlfile/control01.dbf’
This will create a control file in both the ASM Disk group’s +DATA and +FRA. It will also update the control file parameter in the spfile.
If you wish 3 to have control files simply update the control_files parameter to include the original controlfile as well as the ones just created.
Cluster-enable the Standby Database
The standby database now needs to be brought under clusterware control, i.e. registered with Cluster Ready Services.
Before commencing, check that it is possible to start the instance on the second standby node (RAC_STDBY02):
export ORACLE_SID=RAC_STDBY2
sqlplus “/ as sysdba”
startup mount;
Ensure Server Side Load Balancing is configured
Check whether the init.ora parameter remote_listener is defined in the standby instances.
If the parameter is not present then create an entry in the tnsnames.ora files (of all standby nodes) which has the following format:
LISTENERS_RAC_STDBY.local =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = RAC_STDBY01 -vip.local)(PORT = 1521))
(ADDRESS = (PROTOCOL = TCP)(HOST = RAC_STDBY02-vip.local)(PORT = 1521))
)
)
Then set the value of the parameter remote_listener to LISTENERS_ RAC_STDBY.local.
Register the Database with CRS
Issue the following commands to register the database with Oracle Cluster Ready Services:
srvctl add database –d RAC_STDBY –o $ORACLE_HOME –m local –p “+DATA/RAC_STDBY/spfileRAC_STDBY.ora” –n RAC_PRIM –r physical_standby –s mount
srvctl add instance –d RAC_STDBY –i RAC_STDBY1 –n RAC_STDBY01
srvctl add instance –d RAC_STDBY –i RAC_STDBY2 –n RAC_STDBY02
Test
Test that the above has worked by stopping any running standby instances and then starting the database (all instances) using the command:
srvctl start database –d RAC_STDBY
Once started check that the associated instances are running by using the command:
srvctl status database –d RAC_STDBY
Temporary Files
Temporary files associated with a temporary tablespace are automatically created with a standby database.
Create Standby Redo Logs
Standby Redo Logs (SRL) are used to store redo data from the primary databases when the transport is configured using the Logwriter (LGWR), which is the default.
Each standby redo log file must be at least as large as the largest redo log file in the primary database. It is recommended that all redo log files in the primary database and the standby redo logs in the respective standby database(s) be of the same size.
The recommended number of SRLs is :
(# of online redo logs per primary instance + 1) * # of instances .
Whilst standby redo logs are only used by the standby site, they should be defined on both the primary as well as the standby sites. This will ensure that if the two databases change their roles (primary-> standby and standby -> primary) then no extra configuration will be required.
The standby database must be mounted (mount as ‘standby’ is the default) before SRLs can be created.
SRLs are created as follows (the size given below is just an example and has to be adjusted to the current environment):
1. sqlplus ‘ / a sysdba’
2. startup mount
3. alter database add standby logfile SIZE 100M;
NOTE: Standby Redo Logs are also created in logfile groups. But be aware of the fact that group numbers then must be greater than the group numbers which are associated with the ORLs in the primary database. Wrt group numbering Oracle makes no difference between ORLs and SRLs.
NOTE: Standby Redo Logs need to be created on both databases.
The standby database is now created. The next stage in the process concerns enabling transaction synchronisation. There are two ways of doing this:
1. Using SQL Plus
2. Using the Data Guard Broker
Configuring Data Guard using SQL Plus
Configure the Standby Database
The following initialisation parameters need to be set on the standby database:
Parameter Value (RAC_STDBY01 ) Value (RAC_STDBY02)
db_unique_name RAC_STDBY
db_block_checking TRUE (OPTIONAL)
db_block_checksum TRUE (OPTIONAL)
log_archive_config dg_config=(RAC_PRIM, RAC_STDBY)
log_archive_max_processes 5
fal_client RAC_STDBY1.local RAC_STDBY2.local
fal_server ‘RAC_PRIM1.local’, ‘RAC_PRIM2.local’
Standby_file_management Auto
log_archive_dest_2 service=RAC_PRIM LGWR SYNC AFFIRM db_unique_name=PRIMARY_RAC_PRIM VALID_FOR=(ALL_LOGFILES,PRIMARY_ROLE)
log_archive_dest_2 (Max. Performance Mode) service=RAC_PRIM ARCH db_unique_name=PRIMARY_RAC_PRIM VALID_FOR=(ALL_LOGFILES,PRIMARY_ROLE)
Configure the Primary Database
The following initialisation parameters need to be set on the primary database:
Parameter Value (RAC_PRIM01 ) Value (RAC_PRIM02)
db_unique_name RAC_PRIM
db_block_checking TRUE (OPTIONAL)
db_block_checksum TRUE (OPTIONAL)
log_archive_config dg_config=(RAC_PRIM, RAC_STDBY)
log_archive_max_processes 5
fal_client RAC_PRIM1.local RAC_PRIM2.local
fal_server ‘RAC_STDBY1.local’, ‘RAC_STDBY2.local’
standby_file_management Auto
Log_archive_dest_2 service=RAC_STDBY LGWR SYNC AFFIRM db_unique_name=RAC_STDBY VALID_FOR=(ALL_LOGFILES,PRIMARY_ROLE)
Log_archive_dest_2 (Max. Performance Mode) service=RAC_STDBY ARCH db_unique_name=RAC_STDBY VALID_FOR=(ALL_LOGFILES,PRIMARY_ROLE
Set the Protection Mode
In order to specify the protection mode, the primary database must be mounted but not opened.
NOTE: The database must be mounted in exclusive mode which effectively means that all RAC instances but one be shutdown and the remaining instance be started with a parameter setting of cluster_database=false.
Once this is the case then the following statement must be issued on the primary site:
If using Maximum Protection mode then use the command:
Alter database set standby database to maximize protection;
If using Maximum Availability mode then use the command:
Alter database set standby database to maximize availability;
If using Maximum Performance mode then use the command:
Alter database set standby database to maximize performance;
Enable Redo Transport & Redo Apply
Enabling the transport and application of redo to the standby database is achieved by the following:
Standby Site
The standby database needs to be placed into Managed Recovery mode. This is achieved by issuing the statement:
Alter database recover managed standby database disconnect;
Oracle 10gR2 introduced Real Time redo apply (SRLs required). Enabling real time apply is achieved by issuing the statement:
alter database recover managed standby database using current logfile disconnect;
Primary Site:
Set:
log_archive_dest_state_2=enable
in the init.ora file or issue via SQLPlus :
alter system set log_archive_dest_state_2=enable
For Complete and More details, Please refer the following ORACLE HA Best Practices Article:
Data Guard 11g Installation and Configuration Best Practices on Oracle RAC ====================================================================================
