Top 30 Oracle Bpm Interview Questions You Must Prepare 08.Sep.2024

Use this SQL to check

SQL> SELECT sid totalwork sofar FROM v$session_longops WHERE sid 153;

Here give SID when back start it will show SID

Using RMAN BLOCK RECOVER command

RMAN doesn’t support cancel-based recovery like SQL*plus does.

The term obsolete does not mean the same as expired. In short obsolete me “not needed ” whereas expired me “not found.”

A status of “expired” me that the backup piece or backup set is not found in the backup destination. A status of “obsolete” me the backup piece is still available, but it is no longer needed. The backup piece is no longer needed since RMAN has been configured to no longer need this piece after so many days have elapsed, or so many backups have been performed.

1. shutdown Immediate
2. startup mount 
3. Then, run the the DBNEWID utility from command line.
4. nid target =/
5. SQL> alter database open resetlogs;

An auxiliary channel is a link to auxiliary instance. If you do not have automatic channels configured, then before issuing the DUPLICATE command, manually allocate at least one auxiliary channel within the same RUN command. When a Duplicate Database created or table space point in time recovery is performed Auxiliary database is used. This database can either on the same host or a different host.

Differential backup: This is the default type of incremental backup which backs up all blocks changed after the most recent backup at level n or lower.

Cumulative backup: Backup all blocks changed after the most recent backup at level n-1 or lower.

RMAN keeps information of backups in the control file.

Steps to be followed:

• Create connection string at catalog database.
• At catalog database create one new user or use existing user and give that user a recovery_catalog_owner privilege.
• Login into RMAN with connection string
  • export ORACLE_SID
  • rman target catalog @connection string
• rman&g ….

issue command at rman prompt…..

RMAN> configure controlfile autobackup on;

also we can configure controlfile backup format……

RMAN> configure controlfile autobackup format for device type disk to ‘$HOME/BACKUP/RMAN/ F.bkp’; — $HOME/BACKUP/RMAN/ this can be any desired location.

• startup mount;
• restore database UNTIL TIME “TO_DATE(’28/12/2012 18:00:00′, ‘DD/MM/YYYY HH24:MI:SS’)”;
• recover database UNTIL TIME “TO_DATE(’28/12/2012 18:00:00′, ‘DD/MM/YYYY HH24:MI:SS’)”;
• alter database open resetlogs;

RMAN can store backup data in a logical structure called a backup set, which is the smallest unit of an RMAN backup. A backup set contains the data from one or more data files, archived redo logs, or control files or server parameter file.

Crosscheck will be useful to check whether the catalog information is intact with OS level information.

• We need to list the database incarnations by using list incarnation command.
• shutdown the database
• startup mount the database
• Issue reset database to incarnation to reset the incarnation.
• Restore the database using restore command (e.g restore until scn 23243)
• recover database
• Open the database using resetlogs command

RMAN> list incarnation of database;
RMAN>reset database to incarnation 5;
run
{
set until scn 234345;
restore database;
rec  ….

Obsolete backups:

• RMAN> report obsolete;

expired backup:

• RMAN> list expired backup;
• Active database: RMAN> list backup;

No, table based recovery not possible in RMAN duplicate command.

RC_DATABASE_INCARNATION, RC_BACKUP_COPY_DETAILS, RC_BACKUP_CORRUPTION, RC_BACKUP_DATAFILE_SUMMARY to name a few

RMAN> List Backup;

Use the ALLOCATE CHANNEL command to manually allocate a channel, which is a connection between RMAN and a database instance. To enable the parallel backups, allocate multiple manual channels in the run block or configure parallelism

CONFIGURE DEVICE TYPE DISK PARALLELISM 4 BACKUP TYPE TO BACKUPSET;

The restore/validate and validate backupset commands test whether you can restore backups or copies.

You should use:

• restore : validate when you want RMAN to choose which backups or copies should be tested.
• validate backupset when you want to specify which backup sets should be tested.

RMAN backup time consumption is very less than compared to regular online backup as RMAN copies only modified blocks.

• startup mount;
• restore database UNTIL SCN 233545;
• recover database UNTIL SCN 233545;
• alter database open resetlogs;

Recovery catalog is a schema stored in a database that tracks backups and stores of target databases. So better to take a export backup.

The difference is only who maintains the backup records like when is the last successful backup incremental differential etc.

• In CATALOG mode another database (TARGET database) stores all the information.
• In NOCATALOG mode controlfile of Target database is responsible.

Configure channel as SBT_TAPE and use “ENV” parameter to set the tape configurations.

Online redo logs should never, ever be included in a backup, regardless of whether that backup is performed hot or cold. The reasons for this are two-fold. First, you physically cannot backup a hot online redo log, and second there is precisely zero need to do so in the first place because an archive redo log is, by definition, a backup copy of a formerly on-line log. There is, however, a more practical reason: backing up the online logs yourself increases the risk that you will lose.

Use below commands :

• rman> catalog datafilecopy ‘f:testsystem.dbf’;
• rman> backup validate check logical datafile ‘f:testsystem.dbf’;
• SQL> SELECT * FROM v$database_block_corruption;

You can use the CONTROL_FILE_RECORD_KEEP_TIME parameter to specify the minimum number of days that Oracle keeps this information in the control file.

• A level 0 incremental backup, which is the base for subsequent incremental backups, copies all blocks containing data, backing the data file up into a backup set just as a full backup would. A level 1 incremental backup can be either of the following types:
• A differential backup, which backs up all blocks changed after the most recent incremental backup at level 1 or 0
• A cumulative backup, which backs up all blocks changed after the most recent incremental backup at level 0

By using catalog command.You have to catalog that manual backup in RMAN’s repository by command 
RMAN> catalog datafilecopy ‘/DB01/BACKUP/users01.dbf’;
or
RMAN> CATALOG START WITH ‘/tmp/backup.ctl’;
Restrictions:
> Accessible on disk
> A complete image copy of a single file