Oracle Database Administration for Microsoft SQL Server DBAs part 32 ppt

They need to be the ## same size or larger than the primary database SQLPLUS> alter database add standby logfile '/u01/oracle/db01/stby01.log' size 50M; Database altered.. SQLPLUS> alter

Setting Up a Standby Database

An existing database can be configured to have a standby database The first step is to install the Oracle software on the standby server The database already exists on the primary server The primary database will need some configuration with standby logs and parameters Connections to the secondary database can be set up, and then using RMAN, the initial copy of the database can be set up on the standby server

On the primary database, the following needs to be done:

SQLPLUS> alter database force logging;

Database altered.

## Create the standby log files They need to be the

## same size or larger than the primary database

SQLPLUS> alter database add standby logfile

'/u01/oracle/db01/stby01.log' size 50M;

Database altered.

SQLPLUS> alter database add standby logfile

'/u01/oracle/db01/stby02.log' size 50M;

Database altered.

.

## Continue creating the log files One more log group

## than on the primary is recommended

## Parameters

SQLPLUS> show parameter db_name

-

## Name stays the same

SQLPLUS> show parameter db_unique_name

- -

## Standby and Primary will need unique names

## Names do not change even if roles switch

SQLPLUS> alter system set

LOG_ARCHIVE_CONFIG='DG_CONFIG=(db01,dbstby01)'

System altered.

SQLPLUS> alter system set log_archive_dest_2=

'service=dbstby01 async valid_for=(online_logfile,

primary_role) db_unique_name=dbstby01';

System altered.

## The standby database server should already have the

## software and the needed directories for the database

## Create a parameter file for the standby with just the DB_NAME

> cat initdbstby01.ora

DB_NAME=dbstby01

> export ORACLE_SID=dbstby01

SQLPLUS> startup nomount pfile=$ORACLE_HOME/dbs/initdbstby01.ora

ORACLE instance started.

.

SQLPLUS> exit

## To primary database run RMAN to copy database

RMAN> connect target

connected to target database: DB01 (DBID=1382128337)

RMAN> connect auxiliary sysdbstby01

connected to auxiliary database: DBSTBY01 (not mounted)

RMAN> run {

allocate channel disk1 type disk;

allocate auxiliary channel disk2 type disk;

duplicate target database for standby from active database

spfile parameter_value_convert 'db01','dbstby01'

set db_unique_name='dbstby01'

set db_file_name_convert='/db01/','/dbstby01/'

set control_files='/u01/oracle/oradata/dbstby01.ctl'

set fal_client='dbstby01'

set fal_server='db01'

set standby_file_management='AUTO'

set log_archive_config='dg_config=(db01,dbstby01)'

set log_archive_dest_1='service=db01 ASYNC valid_for=

(ONLINE_LOGFILE,PRIMARY_ROLE) db_unique_name=db01';

}

.

## Can test the standby by switching the log file on the primary

> export ORACLE_SID=DB01

SQLPLUS> alter system switch logfile;

System altered.

In summary, the basic steps are as follows:

1 Install the software on the standby server.

2 Configure the parameters on the primary server.

3 Make the connections by updating tnsnames.ora and listener.

4 Use RMAN to copy the database.

SQL Server has a manual process for the management of failover for log shipping The Oracle Data Guard failover can be configured to occur automatically You can use the Data Guard broker and management tools

to set up the automatic failover and manage the standby servers The Data Guard broker needs to be running on both the primary and standby server

A listener entry for the Data Guard broker on the primary and standby servers will help with failover and avoiding TNS errors

## Parameter for starting the broker

SQLPLUS> alter system set DG_BROKER_START=TRUE scope=both;

System altered.

## Example listener entry

(SID_LIST =

(SID_DESC =

(GLOBAL_DBNAME = db01_dgmgrl)

(ORACLE_HOME = /u01/oracle/11.2.0/db_1)

(SID_NAME = db01)

)

.

)

Using the Data Guard broker is similar to starting SQL*Plus from the command line Enter dgmgrl to start the utility and then issue commands

## Create a broker configuration

> dgmgrl

DGMGRL for Linux: Version 11.2.0.1.0 - 64bit Production

Copyright (c) 2000, 2009, Oracle All rights reserved.

Welcome to DGMGRL, type "help" for information.

DGMGRL> create configuration 'DG_DB01'

AS PRIMARY DATABASE is 'db01'

CONNECT IDENTIFIER is 'db01';

Configuration "DG_DB01" created with primary database "db01" DGMGRL> add database 'dbstby01'

AS CONNECT IDENTIFIER is 'dbstby01';

Database "dbstby01" added.

DGMGRL> enable configuration

Enabled.

DGMGRL> show configuration

Protection Mode: MaxAvailability

Databases:

db01 – Primary database

dbstby01 – Physical standby database

Fast-Start Failover: DISABLED

Current status for "DG_DB01': SUCCESS

Other utility commands can be used to do a switchover, which changes

the roles of the servers between primary and standby, or failover, which will fail the primary over to the standby database

The default configuration for Fast-Start Failover is disabled

When it is enabled, it can use triggering events to implement the failover

to the standby server Events include connection loss, instance crash, a

shutdown abort on the primary, and different database health checks such

as loss of a datafile With these events, you can set thresholds to have more

control over when the failover occurs This lets you avoid situations where a small hiccup in the connection or a busy server that doesn’t allow a quick

check will cause the system to failover

The Data Guard configurations can be modified to automate the failover

for certain thresholds If there is more than one standby database, the

FastStartFailoverTargetproperty should be set so that the primary

and standby database reference each other

DGMGRL> edit database DB01 set property FastStartFailoverTarget =

'dbstby01';

DGMGRL> edit database DBSTBY01 set property

FastStartFailoverTarget = 'db01';

DGMGRL> edit configuration set property

FastStartFailoverThreshold = '180';

NOTE

With automatic failover, the DBA can be

assured of continuing service without having

to log in However, the DBA may need to

be concerned about unnecessary failovers

Maximum Availability Architecture includes a combination of these solutions, as shown in Figure 10-5 The Oracle RAC database can be a primary and a standby server When the Maximum Protection option is chosen for the Data Guard configuration, having RAC set up on the standby database will reduce the risk for the logs to be applied Figure 10-5 shows the architecture of the Oracle RAC database with the Data Guard standby database

Interconnect

RAC production database primary site

Interconnect

RAC standby database secondary site

FIGURE 10-5. Oracle Maximum Availability Architecture

ASM in an RAC Environment

We have discussed how it is useful to have the ASM instance available for

the disks of the database, but have not yet looked into the details about how

to manage the instance In the Oracle RAC environment, there needs to be

an ASM instance for every node in the cluster, but one ASM instance can

support multiple instances on that node

Managing ASM Disk Groups

The ASM disk groups serve as containers for consolidating databases and

file systems to be able to use the storage more efficiently and even share

between databases The ASM Configuration Assistant (ASMCA) helps you

create and manage disk groups As shown in Figure 10-6, new disks can be

added to the disk group here, and attributes of the disk group can be edited Other ASMCA options allow you to manage the volumes and file system in

a clustered environment

FIGURE 10-6. Using ASMCA

ASMLib is the support library for ASM It is used for initialize the disk for usage with ASM The Linux package for the ASMLib needs to be installed for usage

>rpm -Uvh oracleasm-2.6.18-8.el5-2.0.4-1.el5.i686.rpm \

oracleasm-support-2.0.4-1.el5.i386.rpm \

oracleasmlib-2.0.3-1.el5.i386.rpm

## Configure ASMLib

>/etc/init.d/oracleasm configure

Configuring the Oracle ASM library driver.

.

## Create disks

>/etc/init.d/oracleasm createdisk ORADATA01 /dev/sda1

Marking disk "/dev/sda1" as an ASM disk:

## To see the disks that were created

>/etc/init.d/oracleasm listdisks

ORADATA01

ORADATA02

ORADATA03

ORADATA04

ASM Configuration Parameters

The ASM instance is really a process and a bit of memory Some

parameters go into the spfile for configuration of this instance These parameters provide the details about the type of instance and where the disks are located for creating the disk groups

■ INSTANCE_TYPE Set to ASM (default is RDBMS)

■ ASM_DISKGROUPS Lists the disk groups that should be

mounted

■ ASM_DISKSTRING A value that indicates where to discover the disks that are available to add to a disk group

■ ASM_POWER_LIMIT Maximum power for rebalancing

operation, a value between 1 and 11 (higher number for faster rebalancing)

The information stored in the ASM instance is the metadata about the

disks, disk groups, names, and directories The Oracle database creates

the data in the files when the disk groups are allocated to a database The

ASMCMDcommand-line utility can help you manage the files It provides a

quick way to find out information about what the ASM instance is managing and where the database files are located You can take backups, make

copies, and move files ASMCMD commands are similar to file commands

in a Linux environment Here are some examples of using ASMCMD:

>asmcmd

ASMCMD> ls –l

State Type Rebal Name

MOUNTED NORMAL N DG_DATA01/

MOUNTED NORMAL N DG_DATA02/

ASMCMD> cd DG_DATA01

ASMCMD> ls –l

Type Redund Striped Time Sys Name

Y ASM/

Y DADEV/

Y DSDEV/

Y SQLTEST/

ASMCMD> cd DADEV

ASMCMD> ls –l

Type Redund Striped Time Sys Name

Y DATAFILE/

Y PARAMETERFILE/

Y TEMPFILE/

N spfileDADEV.ora =>

+DG_DATA01/DADEV/PARAMETERFILE/spfile.269.714035663

## Search for the spfile

ASMCMD> find / spfile*

+DG_DATA01/DADEV/PARAMETERFILE/spfile.269.714035663

+DG_DATA01/DADEV/spfileDADEV.ora

## Check SPACE

ASMCMD> du

Used_MB Mirror_used_MB

## Back up a disk group

ASMCMD> md_backup /bkup/dg1_backup –G 'DG_DATA01'

## The –G parameter is optional; if none chosen, it will

## back up all of the disk groups

## See all connected instances

ASMCMD> lsct

ASMCMD> lsct

DB_Name Status Compatible_version Instance_Name Disk_Group

SQLTEST CONNECTED 11.2.0.1.0 SQLTEST DG_DATA01

These simple commands demonstrate the following:

■ Find out how much space is available on one of the disk groups

■ Find out which instances are connected to which disk groups

■ Find a file

■ Execute a backup of one disk group

With ASM, even though everything is laid out in the directories of the disk groups, creating tablespaces is very simple You just use a CREATE TABLEstatement with a disk group and a size

>export ORACLE_SID=DADEV

>sqlplus

SQLPLUS> create tablespace USER_DATA

datafile '+DG_DATA01' size 2048M;

Tablespace created.

Then you have disk space available for users to start filling up with their tables, objects, and whatever data they need to store

As you have come to expect, OEM also offers a way to manage the ASM disk groups and files Figure 10-7 shows the OEM display of the disk groups

of the ASM instance In OEM, the ASM instance is available from any of the database instances that are using the ASM instance You can mount the disk groups through this OEM view

You can see information about the disks, including the status, the type of redundancy that the disk is configured for, and the space that is allocated and used You can also do some health checks and rebalance the disks Selecting one of the disk groups will drill down into a view of the files on the disks, as shown in Figure 10-8 If you find it difficult to work with the file names with all of those numbers, you can create an alias or rename files

FIGURE 10-7. OEM view of ASM disk groups

FIGURE 10-8. OEM view of files in a disk group