Interview Questions.

Q1. Snapshot Standby Database (updatable Snapshot For Testing)?

A snapshot standby database is a fully updatable standby database that is created by changing a physical standby database right into a image standby database.

Like a bodily or logical standby database, a photo standby database receives and information redo records from a number one database. Unlike a physical or logical standby database, a photograph standby database does not apply the redo information that it gets. The redo information acquired through a photograph standby database is not carried out till the snapshot standby is converted returned into a physical standby database, after first discarding any neighborhood updates made to the snapshot standby database.

Q2. What Are New Features In 11g Data Guard?

Here is some statistics guard category and there enhancement

Data Protection Advanced Compression Lost-write safety Fast-Start Failover

Increase ROI Active Data Guard Snapshot Standby

High Availability Faster Redo Apply Faster failover & switchover Automatic Failover the use of ASYNC

Manageability Mixed Windows/Linux

Q3. What Is The Use Of Fal_server & Fal_client, Is It Mandatory To Set These ?

FAL_SERVER

specifies the FAL (fetch archive log) server for a standby database. The cost is an Oracle Net carrier call, which is thought to be configured well on the standby database machine to point to the favored FAL server.

FAL_CLIENT

specifies the FAL (fetch archive log) consumer name that is used by the FAL provider, configured thru the

FAL_SERVER initialization parameter, to refer to the FAL consumer.

The price is an Oracle Net provider call, which is assumed to be configured well at the FAL server machine to factor to the FAL patron (standby database).

Q4. Steps To Create Physical Standby Database?

Take a full hot backup of Primary database

Create standby manipulate record

Trfer full backup, init.Ora, standby control document to standby node.

Modify init.Ora file on standby node.

Restore database

Recover Standby database(Alternatively, RMAN DUPLICATE DATABASE FOR STANDBY DO RECOVERY can be also used)

Setup FAL_CLIENT and FAL_SERVER parameters on both aspects

Put Standby database in Managed Recover mode

Q5. What Are The Background Processes Involved In Data Guard?

MRP, LSP

Q6. How To Find Out Backlog Of Standby?

Pick round((sysdate – a.NEXT_TIME)*24*60) as “Backlog”,m.SEQUENCE#-1 “Seq Applied”,m.Method, m.Repute

from v$archived_log a, (pick out technique,SEQUENCE#, fame from v$managed_standby in which method like ‘%MRP%’)m wherein a.SEQUENCE#=(m.SEQUENCE#-1);

Q7. What Is The Usage Of Db_file_name_convert Parameter In Oracle Data Guard Setup?

DB_FILE_NAME_CONVERT parameter is utilized in Oracle Data Guard setup that to in standby databases. DB_FILE_NAME_CONVERT parameter are used to update the area of information documents in standby database. These parameter are used while you are the usage of distinct directory shape in standby database examine to number one database information documents location.

Q8. What Is Failover/switchover (or) What Is The Difference Between Failover And Switchover?

Switchover – This is executed while both primary and standby databases are to be had. It is pre-planned.

Failover – This is completed when the number one database is NO longer available (ie in a Disaster). It isn't always pre-planned.

Q9. How Many Standby Databases We Can Create (in 10g/11g)?

Till Oracle 10g, nine standby databases are supported.

From Oracle 11g R2, we are able to create 30 standby databases..

Q10. What Is A Snapshot Standby Database?

11g Snapshot Standby Database

Oracle 11g introduces the Snapshot Standby database which basically is an updateable standby database which has been constituted of a bodily standby database.

We can convert a physical standby database to a snapshot standby database, do a little sort of trying out on a database which is a examine write replica of the modern primary or manufacturing database after which sooner or later revert it to  it’s earlier nation as a bodily standby database.

While the snapshot standby database is open in examine-write mode, redo is being received from the primary database, but is not applied.

After changing it again to a bodily standby database, it's miles resynchronized with the primary by using applying the accumalated redo records which became in advance shipped from the number one database but not applied.

Using a photograph standby, we are capable of do actual time application trying out the usage of close to real time manufacturing records. Very regularly we are required to do production clones for the reason of checking out. But using snapshot standby databases we can meet the equal requirement sparing the effort,time,sources and disk space.

Q11. What Is The Usage Of Log_file_name_convert Parameter In Oracle Data Guard Setup?

LOG_FILE_NAME_CONVERT parameter is used in Oracle Data Guard setup that to in standby databases. LOG_FILE_NAME_CONVERT parameter are used to update the place of redo log documents in standby database. These parameter are used while you are the usage of one of a kind directory structure in standby database evaluate to primary database redo log report location.

Step for Physical Standby

These are the stairs to follow:

Enable pressured logging

Create a password record

Configure a standby redo log

Enable archiving

Set up the primary database initialization parameters

Configure the listener and tnsnames to help the database on both nodes

col call format a20

col thread# layout 999

col series# layout 999

col first_change# layout 999999

col next_change# layout 999999

SELECT thread#, collection# AS “SEQ#”, name, first_change# AS “FIRSTSCN”,

next_change# AS “NEXTSCN”,archived, deleted,completion_time AS “TIME”

FROM v$archived_log

V$ log_history

Q12. What Are The Types Of Oracle Data Guard?

Oracle Data Guard labeled in to 2 types primarily based on way of creation and technique used for Redo Apply.

They are as follows:

Physical standby (Redo Apply era)

Logical standby (SQL Apply Technology)

Q13. Explain Active Data Guard?

11g Active Data Guard

Oracle Active Data Guard allows read-handiest get entry to to a physical standby database for queries, sorting, reporting, net-based get right of entry to, etc., while constantly applying modifications acquired from the production database.

Oracle Active Data Guard also allows using speedy incremental backups while offloading backups to a standby database, and may offer additional benefits of excessive availability and disaster protection in opposition to planned or unplanned outages at the manufacturing web site.

Q14. What Are The Data Guard Parameters In Oracle?

Set Primary Database Initialization Parameters

———————————————-

On the primary database, you outline initialization parameters that manipulate redo trport services whilst the database is in the number one function. There are additional parameters you want to add that manipulate the receipt of the redo statistics and log apply services whilst the primary database is tritioned to the standby role.

 DB_NAME=chicago

DB_UNIQUE_NAME=chicago

LOG_ARCHIVE_CONFIG=’DG_CONFIG=(chicago,boston)’

CONTROL_FILES=’/arch1/chicago/control1.Ctl’, ‘/arch2/chicago/control2.Ctl’

LOG_ARCHIVE_DEST_1=

‘LOCATION=/arch1/chicago/

VALID_FOR=(ALL_LOGFILES,ALL_ROLES)

DB_UNIQUE_NAME=chicago’

LOG_ARCHIVE_DEST_2=

‘SERVICE=boston LGWR ASYNC

VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE)

DB_UNIQUE_NAME=boston’

LOG_ARCHIVE_DEST_STATE_1=ENABLE

LOG_ARCHIVE_DEST_STATE_2=ENABLE

REMOTE_LOGIN_PASSWORDFILE=EXCLUSIVE

LOG_ARCHIVE_FORMAT=%t_p.Cs_percentr.Arc

LOG_ARCHIVE_MAX_PROCESSES=30

Primary Database: Standby Role Initialization Parameters

FAL_SERVER=boston

FAL_CLIENT=chicago

DB_FILE_NAME_CONVERT=’boston’,’chicago’

LOG_FILE_NAME_CONVERT=  ‘/arch1/boston/’,’/arch1/chicago/’,’/arch2/boston/’,’/arch2/chicago/’

STANDBY_FILE_MANAGEMENT=AUTO

Prepare an Initialization Parameter File for the Standby Database

—————————————————————–

Create a text initialization parameter record (PFILE) from the server parameter document (SPFILE) utilized by the number one database; a textual content initialization parameter report can be copied to the standby location and changed. For instance:

CREATE PFILE=’/tmp/initboston.Ora’ FROM SPFILE;

Modifying Initialization Parameters for a Physical Standby Database.

DB_NAME=chicago

DB_UNIQUE_NAME=boston

LOG_ARCHIVE_CONFIG=’DG_CONFIG=(chicago,boston)’

CONTROL_FILES=’/arch1/boston/control1.Ctl’, ‘/arch2/boston/control2.Ctl’

DB_FILE_NAME_CONVERT=’chicago’,’boston’

LOG_FILE_NAME_CONVERT= ‘/arch1/chicago/’,’/arch1/boston/’,’/arch2/chicago/’,’/arch2/boston/’

LOG_ARCHIVE_FORMAT=logp.Ct_p.Cs_%r.Arc

LOG_ARCHIVE_DEST_1=  ‘LOCATION=/arch1/boston/

VALID_FOR=(ALL_LOGFILES,ALL_ROLES)

DB_UNIQUE_NAME=boston’

LOG_ARCHIVE_DEST_2=  ‘SERVICE=chicago LGWR ASYNC  VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE)   DB_UNIQUE_NAME=chicago’

LOG_ARCHIVE_DEST_STATE_1=ENABLE

LOG_ARCHIVE_DEST_STATE_2=ENABLE

REMOTE_LOGIN_PASSWORDFILE=EXCLUSIVE

STANDBY_FILE_MANAGEMENT=AUTO

FAL_SERVER=chicago

FAL_CLIENT=boston

Q15. What Is Physical Standby Database In Oracle Data Guard?

Oracle Standby database are divided into physical standby database or logical standby database based on standby database creation and redo log apply method. Physical standby database are created as precise replica i.E block via block copy of primary database. In bodily standby database tractions show up in primary database are synchronized in standby database by using the use of Redo Apply technique by way of continuously making use of redo statistics on standby database received from number one database.

Physical standby database can offload the backup pastime and reporting activity from Primary database. Physical standby database may be opened for read-simplest tractions but redo observe gained’t take place all through that time. But from 11g onwards the use of Active Data Guard option (greater purchase) you could concurrently open the physical standby database for read-most effective get entry to and apply redo logs received from number one database.

Q16. What Are Different Types Of Modes In Data Guard And Which Is Default?

Maximum performance:

This is the default safety mode.

It gives the highest degree of statistics protection that is viable with out affecting the overall performance of a primary database.

This is achieved through permitting tractions to devote as soon as all redo information generated with the aid of the ones tractions has been written to the web log.

Maximum safety:

This protection mode guarantees that no facts loss will occur if the number one database fails.

To provide this level of protection, the redo facts had to get better a traction ought to be written to both the online redo log and to at least one standby database earlier than the traction commits.

To make sure that information loss cannot occur, the number one database will close down, as opposed to continue processing tractions.

Maximum availability:

This safety mode affords the highest stage of facts protection that is viable without compromising the supply of a number one database.

Tractions do now not dedicate until all redo facts needed to recover those tractions has been written to the online redo log and to as a minimum one standby database.

Q17. What Is Data Guard?

Data Guard offers a comprehensive set of offerings that create, maintain, manage, and screen one or greater standby databases to allow manufacturing Oracle databases to survive failures and records corruptions. Data Guard keeps those standby databases as copies of the manufacturing database. Data Guard may be used with conventional backup, recuperation, and cluster techniques to offer a high degree of records safety and information availability.

Q18. How To Check What Protection Mode Of Primary Database In Your Oracle Data Guard?

By using following query you can test protection mode of primary database on your Oracle Data Guard setup. SELECT PROTECTION_MODE FROM V$DATABASE;

For Example: SQL> choose protection_mode from v$database;

PROTECTION_MODE

——————————–

MAXIMUM PERFORMANCE

Q19. What Is The Difference Between Data Guard And Standby?

Data Guard : Dataguard is mechanism/device to maintain standby database. The dataguard is installation among primary and standby instance . Data Guard is only available on Enterprise Edition.

Standby Database : Physical standby database affords a physically identical replica of the primary database, with on disk database structures which are identical to the number one database on a block-for-block basis. Standby functionality is available on Standard Edition.

Q20. What Is The Difference Between Sync/async, Lgwr/arch, And Affirm/noaffirm ?

Specifies that network I/O is to be done synchronously (SYNC) or asynchronously (ASYNC) whilst archival is completed the usage of the log author method (LGWR).

Specifies whether or not redo trport services use archiver methods (ARCn) or the log author system (LGWR) to acquire traction redo records and trmit it to standby locations. If neither the ARCH or LGWR attributes are designated, the default is ARCH.

Controls whether or not redo trport offerings use synchronous or asynchronous I/O to jot down redo statistics to disk

AFFIRM—specifies that all disk I/O to archived redo log documents and standby redo log documents is completed synchronously and completes efficiently earlier than the log author manner continues.

NOAFFIRM—specifies that all disk I/O to archived redo log files and standby redo log documents is done asynchronously; the log writer system at the primary database does now not wait until the disk I/O completes before persevering with.

Q21. How Can U Recover Standby Which Far Behind From Primary (or) Without Archive Logs How Can We Make Standby Sync?

By using RMAN incremental backup.

Q22. What Are The Services Required On The Primary And Standby Database ?

The services required on the number one database are:

Log Writer Process (LGWR) – Collects redo statistics and updates the web redo logs. It can also      create neighborhood archived redo logs and trmit online redo to standby databases.

Archiver Process (ARCn) – One or greater archiver strategies make copies of on line redo logs either locally or remotely for standby databases.

Fetch Archive Log (FAL) Server – Services requests for archive redo logs from FAL clients strolling on more than one standby databases. Multiple FAL servers may be run on a primary database, one for each FAL request. .

The offerings required on the standby database are:

Fetch Archive Log (FAL) Client – Pulls archived redo log files from the number one website. Initiates trfer of archived redo logs whilst it detects an opening series.

Remote File Server (RFS) – Receives archived and/or standby redo logs from the number one database.

Archiver (ARCn) Processes – Archives the standby redo logs applied with the aid of the controlled healing system (MRP).

Managed Recovery Process (MRP) – Applies archive redo log information to the standby database

Q23. What Are Differences Between Physical, Logical, Snapshot Standby And Adg (or) What Are Different Types Of Standby Databases?

Physical standby – in mount nation, MRP will practice files

ADG – in READ ONLY kingdom, MRP will follow files

Logical standby – in READ ONLY nation, LSP will run

Snapshot standby databases – Physical standby database may be converted to picture standby database, so as to be in READ WRITE mode, can do any sort of testing, then we can convert again picture standby database to physical standby database and start MRP so that you can observe all pending information.

Q24. What Is Logical Standby Database In Oracle Data Guard?

Oracle Standby database are divided into bodily standby database or logical standby database based totally on standby database introduction and redo log apply approach. Logical standby database may be created similar to Physical standby database and later you could alter the structure of logical standby database. Logical standby database makes use of SQL Apply technique to synchronize logical standby database with number one database.

This SQL follow technology converts the acquired redo logs to SQL statements and constantly apply those SQL statements on logical standby database to make standby database regular with number one database. Main benefit of Logical standby database examine to physical standby database is you can use Logical standby database for reporting purpose during SQL apply i.E Logical standby database must be open in the course of SQL observe.

Even even though Logical standby database are opened for study/write mode, tables which are in synchronize with primary database are to be had for read-most effective operations like reporting, pick out queries and including index on the ones tables and developing materialized views on the ones tables. Though Logical standby database has benefit on Physical standby database it has some limit on records-sorts, styles of DDL, sorts of DML and styles of tables.

Q25. What Is Snapshot Standby (or) How Can We Give A Physical Standby To User In Read Write Mode And Let Him Do Updates And Revert Back To Standby?

Till Oralce 10g, create guaranteed restore factor, open in examine write, permit him do updates, flashback to restore point, begin MRP.

From Oracle 11g, convert physical standby to photo standby, allow him do updates, convert to physical standby, begin MRP.

Q26. What Is Staticconnectidentifier Property Used For?

11gr2 new database assets, StaticConnectIdentifier, which lets in the person to specify a static join identifier that the DGMGRL purchaser will use to start database times.

Q27. How To Delay The Application Of Logs To A Physical Standby?

A standby database mechanically applies redo logs whilst they come from the number one database. But in a few instances, we need to create a time lag among the archiving of a redo log at the number one website, and the utility of the log at the standby website online.

Modify the LOG_ARCHIVE_DEST_n initialization parameter on the number one database to set a postpone for the standby database.

Example: For 60min Delay:

ALTER SYSTEM SET LOG_ARCHIVE_DEST_2=’SERVICE=stdby_srvc DELAY=60′;

The DELAY attribute is expressed in minutes.

The archived redo logs are nonetheless robotically copied from the primary site to the standby website, but the logs are not without delay carried out to the standby database. The logs are carried out while the specified time c program languageperiod expires.

Q28. Data Guard Architecture?

Data Guard Configurations:

A Data Guard configuration consists of one production database and one or extra standby databases. The databases in a Data Guard configuration are linked by Oracle Net and may be dispersed geographically. There are no regulations on where the databases are placed, furnished they are able to speak with each different.

 Dataguard Architecture

The Oracle 9i Data Guard structure includes the subsequent items:

Primary Database – A production database this is used to create standby databases. The archive logs from the number one database are trfered and applied to standby databases. Each standby can best be related to a unmarried number one database, however a single number one database can be related to more than one standby databases.

Standby Database – A replica of the primary database.

Log Trport Services – Control the automated trfer of archive redo log documents from the number one database to 1 or more standby locations.

Network Configuration – The primary database is connected to 1 or greater standby databases using      Oracle Net.

Log Apply Services – Apply the archived redo logs to the standby database. The Managed Recovery      Process (MRP) surely does the work of keeping and applying the archived redo logs.

Role Management Services – Control the converting of database roles from number one to standby. The offerings consist of switchover, switchback and failover.

Data Guard Broker – Controls the introduction and monitoring of Data Guard. It comes with a GUI and command line interface.

Primary Database:

A Data Guard configuration includes one production database, also known as the primary database, that features inside the primary position. This is the database this is accessed by most of your packages.

Standby Database:

A standby database is a tractionally constant copy of the primary database. Using a backup reproduction of the number one database, you could create up to nine standby databases and incorporate them in a Data Guard configuration. Once created, Data Guard robotically continues every standby database via trmitting redo data from the primary database and then applying the redo to the standby database.

The forms of standby databases are as follows:

Physical standby database:

Provides a bodily equal reproduction of the number one database, with on disk database systems which might be identical to the number one database on a block-for-block foundation. The database schema, consisting of indexes, are the equal. A bodily standby database is kept synchronized with the number one database, thru Redo Apply, which recovers the redo facts received from the number one database and applies the redo to the physical standby database.

Logical standby database:

Contains the equal logical information as the production database, even though the physical organization and structure of the data may be specific. The logical standby database is saved synchronized with the number one database thru SQL Apply, which trforms the data inside the redo received from the primary database into SQL statements after which executes the SQL statements on the standby database.

Q29. What Are The Advantages Of Logical Standby Database In Oracle Data Guard?

Better utilization of aid

Data Protection

High Availability

Disaster Recovery

Q30. What Are The Advantages Of Using Physical Standby Database In Oracle Data Guard?

Advantages of the usage of Physical standby database in Oracle Data Guard are as follows:

High Availability.

Load balancing (Backup and Reporting).

Data Protection.

Disaster Recovery.

Q31. What Are The Different Services Available In Oracle Data Guard?

Following are the exclusive Services to be had in Oracle Data Guard of Oracle database.

Redo Trport Services.

Log Apply Services.

Role Tritions.

Q32. What Are The Different Protection Modes Available In Oracle Data Guard?

Following are the specific safety modes available in Data Guard of Oracle database you can use any one based in your software requirement.

Maximum Protection

Maximum Availability

Maximum Performance.

Q33. How To Change Protection Mode In Oracle Data Guard Setup?

By the use of following query your can exchange the protection mode for your number one database after putting in required price in corresponding LOG_ARCHIVE_DEST_n parameter in number onePERFORMANCEmodify database set standby database to MAXIMUM PROTECTION;

Q34. Tell Me About Parameter Which Is Used For Standby Database?

Log_Archive_Dest_n

Log_Archive_Dest_State_n

Log_Archive_Config

Log_File_Name_Convert

Standby_File_Managment

DB_File_Name_Convert

DB_Unique_Name

Control_Files

Fat_Client

Fat_Server

The LOG_ARCHIVE_CONFIG parameter permits or disables the sending of redo streams to the standby web sites. The DB_UNIQUE_NAME of the primary database is dg1 and the DB_UNIQUE_NAME of the standby database is dg@The number one database is configured to deliver redo log move to the standby database. In this situation, the standby database provider is dg2.

Next, STANDBY_FILE_MANAGEMENT is ready to AUTO so that once Oracle documents are introduced or dropped from the number one database, those adjustments are made to the standby databases robotically. The STANDBY_FILE_MANAGEMENT is only relevant to the physical standby databases.

Setting the STANDBY_FILE_MANAGEMENT parameter to AUTO is is suggested while using Oracle Managed Files (OMF) on the primary database. Next, the primary database need to be walking in ARCHIVELOG mode.

Q35. What Is Dg Broker?

DG Broker “it's miles the control and monitoring tool”.

Oracle dataguard broker is a distributed control framework that automates and centralizes the creation , renovation and monitoring of DG configuration.

All management operations may be performed either via OEM, which uses the broking (or) broker unique command-line device interface “DGMGRL”.

Q36. What Is Dg_config ?

Specify the DG_CONFIG characteristic to identify the DB_UNIQUE_NAME for the number one database and every standby database inside the Data Guard configuration.

The default fee of this parameter permits the number one database to send redo records to remote destinations and allows standby databases to acquire redo data.

Q37. What Are The Uses Of Standby Redo Log Files?

A standby redo log is required for the most safety and maximum availability modes and the LGWR ASYNC trport mode is suggested for all databases. Data Guard can get better and observe greater redo data from a standby redo log than from archived redo log documents alone.

If the real-time apply feature is enabled, log apply services can observe redo facts as it's miles obtained, without anticipating the cutting-edge standby redo log record to be archived.

This consequences in quicker switchover and failover instances due to the fact the standby redo log documents had been implemented already to the standby database by the point the failover or switchover starts.

Q38. What Are The Differences Between Physical/logical Standby Databases? How Would You Decide Which One Is Best Suited For Your Environment?

Physical standby DB: As the name, it is physically (datafiles, schema, different bodily identification) equal replica of the primary database. It synchronized with the number one database with Apply Redo to the standby DB.

Logical Standby DB: As the call logical statistics is similar to the manufacturing database, it could be physical structure may be exceptional.

It synchronized with number one database even though SQL Apply, Redo obtained from the primary database into SQL statements and then executing these SQL statements on the standby DB.

We can open “bodily stand via DB to “study handiest” and make it available to the applications users (Only select is allowed during this era). We can not practice redo logs acquired from number one database presently.

We do now not see such problems with logical standby database. We can open the database in ordinary mode and make it to be had to the users. At the same time, we can apply archived logs obtained from number one database.

For OLTP huge traction database it's miles higher to pick out logical standby database.

Q39. What Is Rta (real Time Apply) Mode Mrp?

Real-time practice where before log delivery the LGWR method writes to a standbylog report concurrently along with the net redolog report.

This standby logfile is written to standby log report on standby server. There is not any lack of any committed traction in any respect in Real-Time Apply situation.

•In Real Time Apply, as soon as a traction is committed at the Primary, the committed modifications could be to be had at the Standby in Real Time even without switching the log at the Primary

MRP – Managed recuperation technique – For Data Guard, the history procedure that applies archived redo log to the standby database.

Q40. What Are The Protection Modes In Dataguard?

Data Guard Protection Modes

This segment describes the Data Guard protection modes.

In these descriptions, a synchronized standby database is supposed to be one that meets the minimal necessities of the configured statistics protection mode and that doesn't have a redo gap. Redo gaps are mentioned in Section 6.Three.3.

Maximum Availability

This protectionmode gives the best stage of statistics protection that is viable with out compromising the provision of a primary database. Tractions do no longer commit until all redo facts had to get better those tractions has been written to the net redo log and to at the least one synchronized standby database. If the primary database can't write its redo move to at the least one synchronized standby database, it operates as though it had been in most overall performance mode to hold primary database availability until it's far once more capable of write its redo movement to a synchronized standby database.

This mode ensures that no statistics loss will arise if the number one database fails, however most effective if a 2d fault does no longer save you a whole set of redo statistics from being sent from the primary database to as a minimum one standby database.

Maximum Performance

This protectionmode gives the very best degree of facts safety that is possible with out affecting the performance of a primary database. This is achieved by means of allowing tractions to dedicate as soon as all redo records generated by means of those tractions has been written to the online log. Redo facts is likewise written to 1 or extra standby databases, however this is achieved asynchronously with respect to traction dedication, so number one database overall performance is unaffected by way of delays in writing redo records to the standby database(s).

This safety mode gives barely less information protection than maximum availability mode and has minimal effect on primary database overall performance.

This is the default protection mode.

Maximum Protection

This protection mode guarantees that zero statistics loss occurs if a number one database fails. To offer this level of protection, the redo information needed to get better a traction have to be written to both the online redo log and to at the least one synchronized standby database before the traction commits. To ensure that information loss can't occur, the primary database will close down, rather than preserve processing tractions, if it can not write its redo movement to at the least one synchronized standby database.

Because this records protection mode prioritizes records safety over primary database availability, Oracle recommends that at the least two standby databases be used to defend a number one database that runs in most safety mode to prevent a single standby database failure from inflicting the number one database to close down.

Q41. What Is Rts (redo Trport Services) In Data Guard?

It controls the automatic trfer of redo records from the production database to one or greater archival locations.

The redo trport offerings perform the subsequent obligations:

Trmit redo information from the primary machine to the standby structures within the configuration.

Manage the procedure of resolving any gaps in the archived redo log documents due to a network failure.

Automatically detect lacking or corrupted archived redo log documents on a standby machine and automatically retrieve substitute archived redo log documents from the primary database or every other standby database.

Q42. What Are The Advantages In Using Oracle Data Guard?

Following are the distinct benefits in using Oracle Data Guard characteristic on your surroundings:

High Availability.

Data Protection.

Off loading Backup operation to standby database.

Automatic Gap detection and Resolution in standby database.

Automatic Role Trition using Data Guard Broker.