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DataGuardPPT oracle9i

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    Oracle Data Guard

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    Topics to be covered

    What is Oracle Data Guard?

    Oracle 9i Data Guard Features

    New features in 10g

    New features in 11g

    Management Tools

    What are we doing with Data Guard?

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    What is Oracle Data

    Guard?

    Oracle Data Guard is the management,monitoring, and automation softwareinfrastructure that creates, maintains,and monitors one or more standby

    databases to protect data from failures,disasters, errors, and corruption

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    Oracle 9i Data Guard

    Types of Standby Databases

    Creating Standby Databases

    Log Transport Services

    Log Apply Services

    Switchover/Failover

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    Types of Standby

    Databases

    Physical Standby Database

    Logical Standby Database

    Snapshot Standby Database (11g)

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    Types of Standby

    Databases

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    Physical Standby

    Database

    A physical standby database is

    physically identical to the primarydatabase, with on-disk databasestructures that are identical to theprimary database on a block-for-block

    basis. The database schema, includingindexes, must be the same.

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    Physical Standby

    Database Managed Recovery- Physical standby

    is maintained by applying archivedredo logs on the standby using Oraclerecovery operations. Recovery applieschanges on a block for block basis.

    Open Read-Only- Physical standbydatabases can only be queried inRead-Only mode.

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    Physical Standby

    benefits Disaster Recovery/High Availability-

    Switchover/failover allow for role

    reversal of primary and standby,minimizing downtime of primarydatabase.

    Data Protection- Data Guard can ensure

    no data loss with physical standby.

    Reduction in primary database workload-Can take backups from physical standby.

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    Physical Standby

    benefits (cont.)

    Performance- Physical standby is moreefficient than Logical, in that it uses redoapply technology rather than SQL apply.It bypasses SQL level mechanisms, and

    applies redo directly at block level.

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    Logical Standby

    Database Initially created as a copy of primary

    database. Can later be changed.

    Automatically applies archived redo loginfo by transforming data in redo logsinto SQL statements and executing themon the logical standby (must remain

    open).

    Target tables on standby (ones beingupdated from primary) are read only.

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    Logical Standby

    Benefits Efficient use of standby hardware-

    Logical standby can contain other

    schemas than those being updated byData Guard. those other schemas areread/write capable, while those beingmaintained by Data Guard are read only.

    Reduction of Primary DatabaseWorkload- Since standby is open, itsavailable for query (or reporting),offloading work from primary.

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    Snapshot Standby

    Database (11g) Physical standby database that can be

    opened for read/write use. Redo logs arestill received from primary, just notapplied until snapshot standby isconverted back into a physical standby.

    Can have similar functionality with 10gData Guard, however must be donemanually with flashback database.

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    Creating a Physical

    Standby Database

    Make copy of primary database (datafiles)

    Create standby control file on primary

    database

    C ti Ph i l

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    Creating a PhysicalStandby Database

    (cont.)

    Prepare pfile for standby database

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    Standby Parameters

    Defined REMOTE_ARCHIVE_ENABLE-

    Permission to write remote archive

    logs.

    Values: True,False,Send

    DB_FILE_NAME_CONVERT- Converts

    the filename of a datafile on theprimary to a filename onthe standbydatabase. (also paths)

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    Standby Parameters

    Defined LOG_FILE_NAME_CONVERT- Converts the

    filename of a log on the primary

    database to the filename of a log on thestandby database. (Must use if paths aredifferent between primary and standby)

    FAL_SERVER- Assigns the Oracle Netservice name that the standby will useto connect to the fetch archive logserver.

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    Standby Parameters

    Defined FAL_CLIENT- Assigns fetch archive log

    client name to be used by the FAL

    server. This is the Oracle Net servicename that the FAL server should use torefer to the standby database.

    STANDBY_ARCHIVE_DEST- Location onstandby system where archived redologs received from the primary arestored.

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    Standby Parameters

    Defined

    STANDBY_FILE_MANAGEMENT-Automates the creation and deletion ofdatafile filenames on the standby siteusing the same filenames as the primary

    site. Values:auto,manual

    C ti Ph i l

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    Creating a PhysicalStandby Database

    (cont.) Copy files from primary to standby

    system

    On primary system set pfile parameters

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    Primary Parameters

    Defined LOG_ARCHIVE_DEST_2- Specify

    SERVICE=XXXX, XXXX being the

    service name of the standby databaselisted in the tnsnames.ora file on theprimary system. This is the location forthe primary to write its redo.

    LOG_ARCHIVE_DEST_STATE_2- Enables ordisables writing of logs tolog_archive_dest_2. Values: enable,defer, Alternate

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    Primary Parameters

    Defined

    REMOTE_ARCHIVE_ENABLE- Enables ordisables the sending of redo logs toremote destinations and the receipt ofremote redo logs. Values:

    true,false,send,receive (true=send +receive)

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    Creating a PhysicalStandby Database

    (cont.)

    Configure listeners for primary andstandby databases

    Set SQLNET.EXPIRE_TIME=2 in sqlnet.ora

    Modify tnsnames.ora on both primaryand standby

    Create spfile on standby (optional)

    Creating a Physical

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    Creating a PhysicalStandby Database

    (cont.) Start physical standby database

    STARTUP NOMOUNT; ALTER DATABASE MOUNT STANDBY

    DATABASE;

    Initiate log apply services

    ALTER DATABASE RECOVER MANAGEDSTANDBY DATABASE DISCONNECTFROM SESSION;

    Creating a Physical

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    Creating a PhysicalStandby Database

    (cont.) Start remote archiving (from primary)

    ALTER SYSTEM ARCHIVE LOGCURRENT;

    Physical standby database is now up andrunning!

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    Log Transport

    Services

    What are Log Transport services?

    Log Transport Services control theautomated transfer of redo data withina Data Guard configuration. They also

    control the level of data protection foryour database.

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    Data Protection Modes

    Maximum Protection- Highest level ofprotection. A primary database

    transaction will not commit until all redodata needed to recover the transactionhave been written to at least onestandby database, if it cant write to a

    standby, the primary will shutdown.Guarantees no data loss, but has highestimpact on performance of the primarydatabase.

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    Data Protection Modes

    (cont.) Maximum Performance- This is the

    default protection mode. A primary

    database transaction will not wait tocommit until redo data needed torecover the transaction is written to astandby database. This mode provides

    the highest level of protection availablewithout affecting performance oravailability of the primary database.Does not guarantee no data loss.

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    Data Protection Modes

    (cont.) Maximum Availability- Offers 2ndhighest level of protection. Same asMaximum Protection, except if no

    standby database is available theprimary does not shutdown, ittemporarily goes into MaximumPerformance mode until a standby is

    available. This mode guarantees no dataloss except for when in MaximumPerformance mode. It doesnt effect theavailability of the primary like MaximumProtection Mode does.

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    Data Protection Modes

    Maximum ProtectionMaximum Protection Maximum AvailabilityMaximum Availability Maximum PerformanceMaximum Performance

    No Data Loss No Data Loss (except whenin Max Perform)

    Does Not Effect Availability

    Does Not Effect PerformanceDoes Not Effect Availability

    Effects PerformanceEffects Availability

    Effects Performance Possible Data Loss

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    Transporting Redo

    DataMaximum Protection and MaximumAvailability modes both require standby

    redo log files on the standby system.Both use RFS (Remote File Server)process to write to standby redo logs onthe standby database system. Maximum

    Performance mode does not use standbyredo logs when using arch process towrite to standby.

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    Maximum Protection

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    Maximum

    Performance

    Transmission and

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    Transmission andReception of Redo

    Data Specify the process to transmit redo,ARCH or LGWR (ARCH is the default)

    LOG_ARCHIVE_DEST_2=SERVICE=std

    by LGWR

    Choose SYNC or ASYNC networktransmission mode. Must use SYNC forzero data loss.

    LOG_ARCHIVE_DEST_2=SERVICE=stdby ASYNC

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    Data Protection Modes

    MaxProtection

    MaxAvailability

    MaxPerformanc

    e

    Redo Archival Process LGWR LGWR LGWR OR ARCH

    Network TransmissionMode SYNC SYNC ASYNC

    Disk Write Option AFFIRM AFFIRM NOAFFIRM

    Standby Redo LogsRequired? Yes

    Required forPhysical Only

    Only if usingLGWR

    Database Types Physical Physical/Logical Physical/Logical

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    Log Apply Services

    Processes involved in Log apply services(for physical standby)

    Remote File Server (RFS)- Receivesredo data from primary.

    Archiver (ARCn)- Archives standbyredo logs that are to be applied tostandby.

    Managed Recovery Process (MRP)-Applies archived redo logs to standby.

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    Configuring Log Apply

    Services

    Start the Physical Standby:

    To Stop Log Apply Services:

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    Log Apply Services

    To Verify Managed Recovery:

    To Determine if there is an Archive Gap:

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    Monitoring Log Apply

    Services The following views can be used to

    monitor Log Apply Services:

    V$MANAGED_STANDBY

    V$ARCHIVED_LOG

    V$LOG_HISTORY

    V$DATAGUARD_STATUS

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    Switchover/Failover

    Switchover- Role reversal betweenprimary and standby databases. Old

    primary is now a standby. Used forhardware upgrades, OS upgrades, etc.

    Failover- Primary is down with little hopeof quick recovery (ie. hardware failure onprimary machine). Once failover hasbeen initiated, the old primary databaseis no longer useful.

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    How to Perform a

    Switchover On primary database:

    Initiate switchover on primary database:

    After the above statement completes theold primary is now a standby database

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    How to Perform a

    Switchover (cont.)

    While still on old primary shutdowndatabase and restart as standby:

    On the old standby system (newprimary):

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    How to Perform a

    Switchover (cont.) On new primary complete switchover

    then restart database:

    On new standby start managedrecovery:

    On new primary begin redo transport:

    Switchover Complete!

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    How to Perform a

    Failover Manually register any redo logs with the

    standby that are available and that have

    not been applied

    If using standby redo logs, initiatefailover with:

    If not using standby redo logs:

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    How to Perform a

    Failover (cont.) Convert the Physical Standby to Primary

    (modify pfile before restart):

    Failover complete!

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    10g New Features

    Fast Start Failover- Provides the ability toautomatically fail over to a designatedstandby database when the primarygoes down. Automatically reconfiguresold primary as a standby when it re-enters the configuration.

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    10g New Features

    (cont.) Asynchronous Redo Transmission- (LGWR

    ASYNC) has been improved to reduce

    the impact on the primary database(LSNn process added to do redo logtransmission).

    Flashback Database across Data Guard

    Switchovers- Now possible to flash backprimary and standby to an SCN or pointin time prior to switchover operation.

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    11g New Features

    Snapshot Standby- Physical standby that

    can be opened read-write, then revertback to managed recovery.

    Active Data Guard- Physical standby thatcan be opened read-only while redo is

    still applied to the standby. (SUNY is notcurrently licensed for this feature)

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    11g New Features

    (cont.) New advanced compression for redo

    transport. Transient Logical Standby allows a

    physical standby to be changed to alogical standby and then back to a

    physical. Used for rolling databaseupgrades.

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    Management Tools

    SQL - Data Guard can be managed andmonitored with SQL*PLUS. MostlyManual.

    Data Guard Broker- Special interface forData Guard. Has command lineinterface and Java GUI. Less manual than

    SQL*PLUS. Grid Control- Grid control has a web

    based GUI for Data Guard Broker.Enables you to use GC to schedule and

    monitor Data Guard operations

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    What is ITEC doing

    with Data Guard? Currently ITEC is using Data Guard in its

    Data Vaulting service. ITEC currentlyhosts physical standby databases for thefollowing campuses:

    Hudson Valley Community College

    Niagara County Community College

    SUNY Brockport

    SUNY Fredonia

    SUNY Oneonta

    SUNY Oswego

    h i d i

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    What is ITEC doing

    with Data Guard?Currently we are using all Physical

    standby databases. When we startedthe Data Vaulting service, Banner haddata types that were incompatible withlogical standby databases. This may bere-evaluated in the future (newerreleases of Oracle are compatible withmore data types).

    h i C d i

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    What is ITEC doing

    with Data Guard?ITEC currently manages all of its

    physical standby databases using theSQL*Plus interface. Our future intent isto use Grid Control to manage andmonitor all standby databases. ITEC iscurrently in the process of rolling outGrid Control to all systems ITECmanages.

    Wh i ITEC d i

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    What is ITEC doing

    with Data Guard?

    In the Future, when the Dual Data Centerproject is complete, ITEC will replicatethe production databases hosted at ITECto the Albany (Sys Admin) data centerusing either storage level replication orData Guard.


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