Oracle Backup and Recovery Interview Questions

Restoring a database is copying the physical files from a backup medium (disk or tape) to the appropriate file locations for database operation. Recovery is process of updating database files to roll...

Simply the restoration means copy the database object from the backup media to the destination where actually it is required. Whereas recovery means to apply the database object copied earlier in order to bring the database to the consistent state.

Restore: just back up from back up media

recover: during the transaction in case of incomplete transaction due to power failure or some other reasons, that time either to complete the transaction or cancel the transaction is called recover

If the database is in ARCHIVELOG mode we can recover the transactions using archive logs otherwise we can not recover the transactions that are not in the backups.

If a Database is running in NoArchive log mode , when ever log switch happens there will be a loss of some redo log information in order to avoid this, redo logs must be archived. This can be achived by configuring database to run in Archivelog mode

Archive log is for maintaining the database in safest mode. If any data is loss in future, u can easily recover using archive logs. Recover command and reco background process uses archive logs to do ...

Sign on as Oracle, connect to the Target DB on third floor as DBA, and perform your commands.

This only requires a Good OracleNet client arrangement.

Disconnect from your current target DB, and connect to the target DB on the next floor.

This assumes you have connected to the Target DB as DBA, on YOUR floor.

Before shut down better to take up the back up of the database and then disconnect the database and then shutdown the database

There are the following steps of shutting down the database and it's associated instance:1)Close the database.2) Unmount the database.3)Shut down the instance.1) Close a database:When we close the...

inconsistent backup means online backup . when v r doing the online backup the database will be running and query ill be hitting the server in that time scn no ill differ from header of the datafile and the control file . so the both the info will be differ from each other in inconsistent backup 

When begin backup command is issued the datafile header's are blocked. While the controlfile SCN does gets changed. During startup of the database the database has to do a rollforward based on the SCN between the header of datafile and control file.

Thanks
Narendra

1.set the remote_login_passwordfile='EXCLUSIVE'

2.orapwd  file=pwdsid.ora password=xxxxxx  force=y

we have to check the password file is created or not using the following query

SQL> select * from v$pwfile_users;

There are two types of authenticationsOS levelDB levelFor OS level authentication:1. Shutdown the database2. Set OS_AUTHENT_PREFIX=' '    in init.ora file3.$ connect  '...

Steps for Physical standby for Oracle 9i in LINUX.On Primary Side 1. Take rman fullbackup with controlfile and spfile.2. Take standby controlfile backup as SQL> ALTER DATABASE CREATE STANDBY CONTRO...

Creating a physical standby using RMAN

In this critical situation I had a pritical example which follows this.SQL> recover database until cancel using backup controlfile;ORA-00279: change 9867098396261 generated at 03/21/2008 13:37:44 n...

In this situation you're not able to recover the database. Of course, it can be done by using nonsupported and nondocumented parameter "_ALLOW_RESETLOGS_CORRUPTED" but you HAVE NOT to us...

Yes we can use it... RMAN can convert the datafiles from little endian to big endian... The only exception is that both the databases have to use the same national character set and character set...

NO, Because here OS is different this cold backup can be used in solaris only.

OS Corruption doen't mean hard disk crashed.Connect this hard disk as secondary device in a working system, copy the back files/folder to other location, and proceed.

Cannot be recovered.

CONFIGURE allows you to set options and have the setting stick around (persistence)

common things to set:
SNAPSHOT CONTROLFILE NAME
RETENTION POLICY
CHANNEL DEVICE TYPE
CONTROLFILE AUTOBACKUP

See what is set (or standing default values now)
SHOW ALL;

assumes the use of a recovery catalog

show all; command at RMAN will show all configure command in default or update configuration mode

The rman process runs in case of backup running in parallel multiple such processes would run.

select sid,program,osuser,status from v$session where program like '%rman%' query will give the status of such sessions.

I suppose no other database background process is performed. RMAN appears as usual client for database. So, there are only several RMAN processes launched in OS, but no database background processes.

RMAN catalog is a usual database, so just backup is with RMAN as any other database, using it as target database:

Yes, Schedule a Schema level Export backup of the RMAN Catalog Database in Task Scheduler or CRON Exporting the Recovery Catalog This example uses the Original Export utility described in Oracle Dat...

Whenever you have competing DML running against the same data, you run the risk of a deadlock.Tune the application - Single-threading related updates and other application changes can often remove dea...

A deadlock occurs when two or more users are waiting for data locked by each other(Not commited by user01).To fix this, recreate the segment with higher INITTRANS and/or PCTFREE values. This will allo...

When a user managed Hot backup is executed, the tablespace or database has to be placed in backup mode. This informs the Oracle kernel that SCNs should not be updated on the datafile. i.e. the header ...

During begin backup mode, the data file headers get freezed and it doesn’t get updated until the end backup. So it causes a checkpoint to the datafile.  This causes all dirty blocks to be w...

Recovery is method of making the database consitent.  The database keeps this by way of SCN in headrer of all the datafile and controlfile. In case the SCN on datafile and controlfile database th...

Media recovery is used to recover from a damaged(or lost) datafile, controlfile, or spfile. The goal of media recovery is to restore database integrity.

I would suggest create a db link in Oracle 8 to Oracle 9i and run the CREATE TABLE AS SELECT FROM another database.

I would suggest you move to Oracle 10g /11g soon as Oracle support is already stopped to 9i and 8i release.

Narendra

we can do it. but first we have to confirm that parameter NLS_LANG is same in both database. otherwise in IMP process oracle will give error

Use RMAN Backup validate database.

in rman list recoverable backup of database

Restricted mode comes into picture when your taking backup and maintance activites. In the restricted mode no user is allowed to access..
Bring the database to mount , that it will makes Restricted mode active.

RESTRICT is one of an important option used with an open database.It performs a database startup with the database in the restricted user mode. User must having the privileges of RESTRICT, u...