Interview Questions.

Question 1. What Is Scn?

Answer :

The SCN is an Oracle server–assigned range that shows a dedicated model of the database. It’s pretty feasible that special datafiles within the database might have a extraordinary SCN at any given factor in time.

At checkpoint, the server will makes all database file SCNs and control file SCN constant with admire to an identical SCN.The datafiles will no longer incorporate any database modifications past that common SCN. This synchronization of the SCNs will make sure we've got a consistent backup of database.

When you are doing warm backup, you may emerge as with backups of the numerous datafiles at diverse time points and one of a kind SCNs and you cannot open a database with out synchronizing the SCN on all data documents, so that you will should apply archive logs to make the statistics present day and synchronize the SCNs throughout the datafiles.

Question 2. What Is The Significance Of Fast_start_mttr_target Parameter?

Answer :

You use the Oracle initialization parameter fast_start_mttr_target to specify the wide variety of seconds you need the crash restoration to take. Oracle will attempt to get better the

example as near as feasible to the time which you specify for the fast_start_mttr_target parameter. The maximum fee of this parameter is 3600 seconds (1 hour).

During example healing, inside the first roll ahead operation, the database server should observe all transactions among the remaining checkpoint and the end of the redo log to the datafiles. Thus, if you want to tune example healing, you manipulate the distance among the checkpoint function and the quit of the redo log. This is called Mean Time to Recover (MTTR).

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Question 3. There Was A Media Failure. How Can You Find Which Files You Must Recover?

Answer :

By querying the V$RECOVER_FILE view, which lists all documents that want media healing.

Question 4. What Are The Benefits Of Rman Over User-managed Backup-restoration Process?

Answer :

 effective Data Recovery Advisor function

easier backup and healing commands
robotically manages the backup files with out DBA intervention.
Routinely deletes useless backup datafiles and archived redo log documents each from disk and tape.
Gives you with exact reporting of backup actions
Easy to replicate a database or create standby database.
Without honestly restoring statistics, you could take a look at whether you'll be able to do it or no longer
Incremental backup! Handiest RMAN can do that.
Active Duplication! (11g new feature), you may perform database duplication without backups by the use of the network enabled database duplication feature
robotically detects corrupt records blocks at some stage in backups
Data block level recovery possible in case only few DB blocks are corrupt
Encrypted backups feasible
Use RMAN with an expansion of third-celebration garage systems effortlessly
With so many advantages, RMAN shold be used as number one backup-restoration tool.

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Question 5. How Important Is Database Redundancy Set And Where You Should Plan To Keep It?

Answer :

Database Redundancy Set is vital set of recuperation-related documents. As a DBA, you want to be properly prepared for any kind of contingency scenario.

It ought to incorporate beneath:

Recent backups of all datafiles & control record (duplex or triplex the manipulate document at database degree)
All archived redo logs made after the closing backup
Current manipulate files and on-line redo report copies (duplex online redo documents at database degree)
Oracle database-related configuration report copies (spfile, password record, tnsnames.Ora and listener.Ora documents and many others)
Operating device mirroring is good, but you need to do database degree mirroring anyplace possible.

If you the usage of ASM, try to have atleast Normal redundancy.

When setting up manufacturing structures, use as a minimum two disk drives(one for the redundancy set and the opposite for the datafiles). They have to be absolutely separated by the usage of specific volumes, record systems, disk controllers, and RAID gadgets to hold the 2 units of files

You can installation FRA for retaining the redundancy set. Oracle recommends the flash recuperation region as a logical candidate to keep a copy of all the files belonging to the redundancy set (which includes the most current database backup) on disk.

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Question 6. What Is The Benefit Of Making Automatic Control File Backup To On?

Answer :

Remember that manipulate report is sincerely essential at some point of a recuperation.

Below command can be used to have automatic manage record backup to be taken. This is distinctly encouraged.

RMAN> configure controlfile autobackup on Now on the give up of each RMAN backup command, RMAN routinely backs up the manage file.

Even when you make some modifications via SQL*Plus( say developing a new tablespace or including or renaming a datafile or an online redo log member), the manipulate record is routinely sponsored up.

Also, you may restore RMAN’s backup and restoration data (referred to as RMAN’s repository), whilst you lose all your manage documents and aren’t the usage of the optionally available healing catalog.

Question 7. What All You Can Store In Flash Recovery Area(fra)? Can One Fra Directory Be Used For More Than One Database?

Answer :

Oracle can keep specific sort of files under FRA:

backupset: for RMAN everyday backups.
Datafile: for RMAN photograph copies.
Autobackup: for control file autobackups.
Flashback: If your database runs in flashback mode, you may see flashback logs in this subdirectory.
Archivelog: for Archived redo logs
controlfile: The control report, if configured to visit the flash recuperation place.
Onlinelog: Online redo logs also can be made to go to the flash recovery region
You can use the equal flash recovery area for as many databases as you want. The RMAN backup system will create a subdirectory called <SID_NAME>, the same name because the database you are backing up.

Oracle DBA Tutorial Oracle 11g Interview Questions
Question eight. Which Views Can Be Used For Checking Space Usage In The Fra?

Answer :

Check Below..

SQL> choose NAME,SPACE_LIMIT/1024/1024/1024 TOTAL_GB,SPACE_USED/1024/1024/1024 USED_GB,SPACE_RECLAIMABLE,NUMBER_OF_FILES from v$recovery_file_dest;

NAME TOTAL_GB USED_GB SPACE_RECLAIMABLE NUMBER_OF_FILES
————————————————– ———- ———- —————– —————

/u01/oracle/DB11G/fast_recovery_area 16 1.13197899 zero 3
SQL> choose * from v$flash_recovery_area_usage;

FILE_TYPE PERCENT_SPACE_USED PERCENT_SPACE_RECLAIMABLE NUMBER_OF_FILES——————– —————— ————————- —————

CONTROL FILE zero zero zero
REDO LOG zero 0 zero
ARCHIVED LOG .12 0 1
BACKUP PIECE 6.Ninety five zero 2
IMAGE COPY zero zero 0
FLASHBACK LOG zero 0 zero
FOREIGN ARCHIVED LOG zero 0 zero

7 rows decided on.

Question nine. Is Putting Control File And Online Redo Logs In Flash Recovery Area (fra) Advisable?

Answer :

Control record is very essential document for the database operation. Loosing a unmarried manage report will make the database unstable and could lead to interruption in carrier.

So we will usually try and positioned manipulate record in a safe and strong region.

Similarly on line logs are equally critical and loosing them also can reason database to crash, incomplete healing and viable records loss.

CASE 1:

Usually the flash restoration location and the main database disks are positioned in any such way that the possibility of both going down at the equal time is very narrow.

And If your flash healing vicinity is in a garage vicinity as dependable as the main database storage, then you definately have to positioned one control file and one redo member/log organization there.

It will genuinely assist you in short and whole recuperation.

CASE 2:

If your flash restoration location is NOT as reliable as the primary database storage, the threat of failure inside the flash recuperation vicinity is extra as compared to the main database disks. If the flash healing location fails, then you definitely lose one of the manage documents and the net redo log. You can be capable of start database easily by using disposing of that control file from the manage record parameter inside the initialization parameter file (copying online log from the secondary Non-FRA area) and restarting it but you'll have an interruption of production service, which could be very unwanted.

Scenario A: Besides FRA, we've multiplexed Control files to 2 other separate vicinity, so danger of loosing control report (and worry of no longer able to do complete recuperation) is minimized We won’t be setting even a single manage record inside the FRA.

Scenario B: Besides FRA, we've got multiplexed Control documents to only an additional separate place, so hazard of loosing manipulate report and (and worry of now not capable of do complete healing) is greater. Complete restoration of database is of number one importance to you than the database interruption.

Here we will pass and positioned the control file in FRA.

Oracle RAC/ASM Interview Questions
Question 10. How Can You Make Sure That Only One Of The Redo Log Member Is Created In Fra?

Answer :

If you need only one member of the group inside the flash recuperation vicinity and the opposite one in the everyday database report vicinity, you must define  parameters—the flash recovery vicinity and db_create_file_dest.

SQL> Show parameter db_recovery_file_dest
NAME TYPE VALUE
———————————— ———– ——————————
db_recovery_file_dest string /u01/oracle/DB11G/fast_recovery_area
SQL> adjust system set db_create_file_dest =’/u01/oracle/DB11G/oradata’;
System altered.
SQL> alter database upload logfile group 4;
Database altered.
SQL> select * from v$logfile;

GROUP# STATUS TYPE MEMBER IS_RECOVERY_DEST_FILE

three ONLINE /u01/oracle/DB11G/oradata/brij/redo03.Log NO
2 ONLINE /u01/oracle/DB11G/oradata/brij/redo02.Log NO
1 ONLINE /u01/oracle/DB11G/oradata/brij/redo01.Log NO
4 ONLINE /u01/oracle/DB11G/oradata/brij/BRIJ/onlinelog/o1_mf_5_9hl8zjmt_.Log NO
4 ONLINE /u01/oracle/DB11G/fast_recovery_area/BRIJ/onlinelog/o1_mf_5_9hl8zjsz_.Log YES

Oracle 11g Tutorial
Question eleven. How Can You Create Log Of Your Rman Activity?

Answer :

Two methods to do it

A) WHILE STARTING RMAN
$ rman log=’tmp/rman_log.Log’ OR $ rman log /tmp/rman_log.Log append
(use with append clause in case you don’t wanna overwrite present report)

Also If you're going for walks RMAN interactively and also you need to peer output to your terminal display as well as have it written to a log document tee /tmp/rman.Log

B) WHILE INSIDE RMAN
$rman
RMAN> spool log to ‘/tmp/rman_log.Log’;
(use with append clause if you don’t wanna overwrite existing record “spool log to ‘/tmp/rman_log.Log’ append.)
..
RMAN> spool log off;
** you could use any writeable directory and log document name.

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Question 12. Can Recovery Catalog Database Also Be Shutdown From Rman Prompt Like Target Database Can Be Done?

Answer :

All the shutdown and startup instructions applies only to the goal database. You can’t start and prevent the recovery catalog instance from RMAN. The handiest manner to begin up and close down the healing catalog example is by connecting to the restoration catalog database because the target database and by way of issuing the relevant commands to start or prevent the instance.

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Question thirteen. How To Check The Syntax Of Rman Commands?

Answer :

Start the RMAN purchaser with the working gadget command-line argument checksyntax.

$ rman checksyntax
Recovery Manager: Release eleven.2.Zero.4.Zero – Production on Wed 
RMAN> connect goal /

The command has no syntax errors
RMAN> backup database;

The command has no syntax errors

You also can use the checksyntax argument to check the syntax of RMAN commands which might be part of a command document.

Example:
$ rman checksyntax @/tmp/rmancmdfile

Question 14. Does Using Recovery Catalog Means Rman Won’t Use The Control File To Store Information?

Answer :

No. Even whilst you pick to apply a healing catalog, backup facts will continue to be stored inside the control file as nicely by way of default.

Question 15. What Is The Benefit Of Using Recovery Catalog?

Answer :

gives large storage potential, for that reason enabling get right of entry to to an extended records of backups
you can create and keep RMAN scripts in the restoration catalog and Any customer that can connect to the healing catalog and a goal database can use these saved scripts
Can service many target databases
you may use ‘KEEP FOREVER’ clause of RMAN backup command.
Allows you to listing the facts files and tablespaces which might be or  have been in the target database at a given time
Database Administration Interview Questions
Question sixteen. What Is The Significance Of ‘resync Catalog’ Rman Command?

Answer :

The resync catalog command is used with a view to replace or resynchronize a restoration catalog from the target database control file. Since sync is accomplished from Target database control document, so you should connect to the healing catalog in addition to to the target database on the way to carry out the resynchronization.

RMAN> resync catalog;
beginning complete resync of recovery catalog
full resync whole

When above command is achieved, RMAN will first create a photograph control record. It’ll then examine the contents of the recuperation catalog to the contents of the photograph manipulate report and replace the recuperation catalog by means of adding the lacking data and editing the changed backup and schema related statistics.

It manner that we can maintain parameter control_file_record_keep_time longer than our backup c language, in order that the facts within the control record receives transferred to the restoration catalog earlier than that records is overwritten.

When you problem certain RMAN commands which include the backup command, RMAN robotically performs a resynchronization.

Question 17. You Want To Move Your Recovery Catalog From One Database To Another. How You Can Do It?

Answer :

Moving Recovery catalog to some other database is simple method

Create a brand new restoration catalog in the goal database. You don’t want to sign in any database to it
Use the import catalog command in RMAN after connecting to the goal database:
$ rman
RMAN> join catalog rman_new/rman@target_database
RMAN> import catalog rman_old/rman@source_database;
The import catalog command will import the supply healing catalog contents into the goal recuperation catalog.

Oracle Exadata Database Interview Questions
Question 18. What Are The Most Important Recovery Catalog Views?

Answer :

Below are some of the regularly used perspectives:

RC_STORED_SCRIPT: Information approximately RMAN scripts stored in the restoration catalog.
RC_UNUSABLE_BACKUPFILE_DETAILS: Lists the unusable backup files recorded within the recuperation catalog.
RC_RMAN_STATUS: Similar to V$RMAN_STATUS view and shows the reputation of all RMAN operations. This view doesn’t incorporate statistics approximately any operations that are currently executing.
RC_RMAN_CONFIGURATION: Information about persistent configuration settings.
RC_DATAFILE: Shows all datafiles registered in the recovery catalog.
RC_DATABASE: Shows the databases registered in the restoration catalog.
RC_ARCHIVED_LOG: Provides historical statistics on each archived as well as unarchived redo logs.
Oracle DBA Interview Questions
Question 19. How To Check The Version Of Your Recovery Catalog?

Answer :

You can effortlessly test the model of your recuperation catalog by issuing the subsequent command from SQL*Plus after logging in as the healing catalog proprietor:

RMAN@rmandb > choose * from rcver;
VERSION
—————
eleven.02.00.04

Question 20. What All Files Can Not Be Backed Up By Rman?

Answer :

Oracle home-associated files
External files
Network configuration documents
Password files
Oracle Streams Interview Questions