What is difference between Restoring and Recovery of database?
Restoring means copying the database object from the backup media to the destination where actually it is required where as recovery means to apply the database object copied earlier (roll forward) in order to bring the database into consistent state.
What is the difference between complete and incomplete recovery?
An incomplete database recovery is a recovery that it does not reach to the point of failure. The recovery can be either point of time or particular SCN or Particular archive log specially incase of missing archive log or redolog failure where as a complete recovery recovers to the point of failure possibly when having all archive log backup.
How would you decide your backup strategy and timing for backup?
In fact backup strategy is purely depends upon your organization business need.
If no downtime then database must be run on archivelog mode and you have to take frequently or daily backup.
If sufficient downtime is there and loss of data would not affect your business then you can run your database in noarchivelog mode and backup can be taken in-frequently or weekly or monthly.
In most of the case in an organization when no downtime then frequent inconsistent backup needed (daily backup), multiplex online redo log files (multiple copies), different location for redo log files, database must run in archivelog mode and dataguard can be implemented for extra bit of protection.
What is the benefit of running the DB in archivelog mode over no archivelog mode?
When a database is in no archivelog mode whenever log switch happens there will be a loss of some redoes log information in order to avoid this, redo logs must be archived. This can be achieved by configuring the database in archivelog mode.
If an oracle database is crashed? How would you recover that transaction which is not in backup?
If the database is in archivelog we can recover that transaction otherwise we cannot recover that transaction which is not in backup.
What is the difference between HOTBACKUP and RMAN backup?
For hotbackup we have to put database in begin backup mode, then take backup where as RMAN would not put database in begin backup mode. RMAN is faster can perform incremental (changes only) backup, and does not place tablespace in hotbackup mode.
Can we use Same target database as Catalog database?
No, the recovery catalog should not reside in the target database (database to be backed up) because the database can not be recovered in the mounted state.
Incremental backup levels:
Level 0 – full backup that can be used for subsequent incrementals
RMAN> backup incremental level 0 database;
Differential Level 1–only the blocks that have changed since the last backup (whether it is level 0 or level 1)
RMAN> backup incremental level 1 differential database;
Cumulative Level 1 – all changes since the last level 0 incremental backup
RMAN> backup incremental level 1 cumulative database;
A full backup cannot be used for a cumulative level 1 backup.
A cumulative level 1 backup must be done on top of an incremental level 0 backup.
Why RMAN incremental backup fails even though full backup exists?
If you have taken the RMAN full backup using the command ‘Backup database’, where as a level 0 backup is physically identical to a full backup. The only difference is that the level 0 backup is recorded as an incremental backup in the RMAN repository so it can be used as the parent for a level 1 backup. Simply the ‘full backup without level 0’ can not be considered as a parent backup from which you can take level 1 backup.
Can we perform RMAN level 1 backup without level 0?
If no level 0 is available, then the behavior depends upon the compatibility mode setting (oracle version).
If the compatibility mode less than 10.0.0, RMAN generates a level 0 backup of files contents at the time of backup.
If the compatibility is greater than 10.0.0, RMAN copies all block changes since the file was created, and stores the results as level 1 backup.
How to put Manual/User managed backup in RMAN?
In case of recovery catalog, you can put by using catalog command:
RMAN> CATALOG START WITH ‘/oracle/backup.ctl’;
How to check RMAN version in oracle?
If you want to check RMAN catalog version then use the below query from SQL*plus
SQL> Select * from rcver;
What happens actually in case of instance Recovery?
While Oracle instance fails, Oracle performs an Instance Recovery when the associated database is being re-started. Instance recovery occurs in 2 steps:
Cache recovery: Changes being made to a database are recorded in the database buffer cache as well as redo log files simultaneously. When there are enough data in the database buffer cache, they are written to data files. If an Oracle instance fails before these data are written to data files, Oracle uses online redo log files to recover the lost data when the associated database is re-started. This process is called cache recovery.
Transaction recovery: When a transaction modifies data in a database (the before image of the modified data is stored in an undo segment which is used to restore the original values in case the transaction is rolled back). At the time of an instance failure, the database may have uncommitted transactions. It is possible that changes made by these uncommitted transactions have gotten saved in data files. To maintain read consistency, Oracle rolls back all uncommitted transactions when the associated database is re-started. Oracle uses the undo data stored in undo segments to accomplish this. This process is called transaction recovery.
What is RMAN?
Recovery Manager (RMAN) is a utility that can manage your entire Oracle backup and recovery activities.
What is the difference between using recovery catalog and control file?
When new incarnation happens, the old backup information in control file will be lost. It will be preserved in recovery catalog.
In recovery catalog we can store scripts.
Recovery catalog is central and can have information of many databases.
Can we use same target database as catalog?
No, The recovery catalog should not reside in the target database (database should be backed up), because the database can’t be recovered in the mounted state.
How do you know that how much RMAN task has been completed?
By querying v$rman_status or v$session_longops
From where list & report commands will get input?
Both the commands command quering v$ and recovery catalog views. V$BACKUP_FILES or many of the recovery catalog views such asRC_DATAFILE_COPY or RC_ARCHIVED_LOG.
Command to delete archive logs older than 7days?
RMAN> delete archivelog all completed before sysdate-7;
How many times does oracle ask before dropping a catalog?
The default is two times one for the actual command, the other for confirmation.
How to view the current defaults for the database.
RMAN> show all;
What is the use of crosscheck command in RMAN?
Crosscheck will be useful to check whether the catalog information is intact with OS level information. This command only updates repository records with the status of the backups.
e.g. If user removes archived logs from disk with an operating system command, the repository still indicates that the logs are on disk, when in fact they are not.
What are the differences between crosscheck and validate commands?
Validate command is to examine a backup set and report whether it can be restored. RMAN scans all of the backup pieces in the specified backup sets and looks at the checksum to verify that the contents are intact so that backup can be successfully restored if necessary.
Crosscheck command is to verify the status of backups and copies recorded in the RMAN repository against media such as disk or tape. The crosscheck command only processes files created on the same device type as the channel running crosscheck.
Which one is good, differential (incremental) backup or cumulative (incremental) backup?
A differential backup, which backs up all blocks changed after the most recent incremental backup at level 1 or 0
RMAN> BACKUP INCREMENTAL LEVEL 1 DATABASE;
A cumulative backup, which backs up all blocks changed after the most recent incremental backup at level 0
RMAN> BACKUP INCREMENTAL LEVEL 1 CUMULATIVE DATABASE;
Cumulative backups are preferable to differential backups when recovery time is more important than disk space, because during recovery each differential backup must be applied in succession. Use cumulative incremental backups instead of differential, if enough disk space is available to store cumulative incremental backups.
This is command for taking Level 0 backup.
RMAN> BACKUP INCREMENTAL LEVEL 0 DATABASE;
What is the difference between backup set and backup piece?
Backup set is logical and backup piece is physical.
RMAN command to backup for creating standby database
RMAN> duplicate target database
You loss one datafile and DB is running in ARCHIVELOG mode. You have full database backup of 1 week/day old and don’t have backup of this (newly created) datafile. How do you restore/recover file?
Create data file and recover datafile.
SQL> alter database create datafile ‘/u01/app/oracle/oradata/xyz.dbf’ size 2G;
RMAN> recover datafile file_id;
What is obsolete backup & expired backup?
A status of “expired” means that the backup piece or backup set is not found in the backup destination.
A status of “obsolete” means 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.
What is the difference between hot backup & RMAN backup?
For hot backup, we have to put database in begin backup mode, then take backup.
RMAN won’t put database in backup mode.
How to put manual/user-managed backup in RMAN (recovery catalog)?
By using catalog command.
RMAN> CATALOG START WITH ‘/tmp/backup.ctl’;
What are the Architectural components of RMAN?
RMAN Executables
Sercer process
Channels
Target database
Recovery catalog database (optional)
Media management Layer (optional)
Backups, backup sets and backup pieces
What are channels?
A channel is an RMAN server process started when there is a need to communicate with an I/O device, such as a disk or a tape. A channel is what reads and writes RMAN backup files. It is through the allocation of channels that you govern I/O characteristics:
Type of I/O device being read or written to, either a disk or an sbt_tape
Number of processes simultaneously accessing an I/O device
Maximize size of files created on I/O devices
Maximize rate at which database files are read
Maximize number of files open at a time
Why is the catalog optional?
Because RMAN manages backup and recovery operations, it requires a place to store necessary information about the database. RMAN always stores this information in the target database control file. You can also store RMAN metadata in a recovery catalog schema contained in a separate database. The recovery catalog schema must be stored in a database other than the target database.
What is a Backup set?
A logical grouping of backup files — the backup pieces — that are created when you issue an RMAN backup command. A backup set is RMAN’s name for a collection of files associated with a backup. A backup set is composed of one or more backup pieces.
What are the benefits of using RMAN?
Incremental backups that only copy data blocks that have changed since the last backup.
Tablespaces are not put in backup mode, thus there is noextra redo log generation during online backups.
Detection of corrupt blocks during backups.
Parallelization of I/O operations.
Automatic logging of all backup and recovery operations.
Built-in reporting and listing commands.
What are the various reports available with RMAN
RMAN>list backup;
RMAN> list archive;
In catalog database, if some of the blocks are corrupted due to system crash, How will you recover?
using RMAN BLOCK RECOVER command
How do you enable the autobackup for the controlfile using RMAN?
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
2> ‘$HOME/BACKUP/RMAN/ F.bkp’;
How do you identify what are the all the target databases that are being backed-up with RMAN database?
You don’t have any view to identify whether it is backed up or not. The only option is connect to the target database and give list backup this will give you the backup information with date and timing.
How do you identify the block corruption in RMAN database? How do you fix it?
Using v$block_corruption view you can find which blocks corrupted.
RMAN> block recover datafile <fileid> block <blockid>;
Using the above statement You recover the corrupted blocks. First check whether the block is corrupted or not by using this command
SQL>select file# block# from v$database_block_corruption;
file# block
2 507
the above block is corrupted…
conn to Rman
To recover the block use this command…
RMAN>blockrecover datafile 2 block 507;
the above command recover the block 507
Now just verify it…..
Rman>blockrecover corruption list;
How do you clone the database using RMAN software? Give brief steps? When do you use crosscheck command?
Check whether backup pieces proxy copies or disk copies still exist.
Two commands available in RMAN to clone database:
1) Duplicate
2) Restore.
List some of the RMAN catalog view names which contain the catalog information?
RC_DATABASE_INCARNATION RC_BACKUP_COPY_DETAILS
RC_BACKUP_CORRUPTION
RC_BACKUP-DATAFILE_SUMMARY
How do you install the RMAN recovery catalog?
Steps to be followed:
1) Create connection string at catalog database.
2) At catalog database create one new user or use existing user and give that user a recovery_catalog_owner privilege.
3) Login into RMAN with connection string
a) export ORACLE_SID
b) rman target catalog @connection string
4) rman> create catalog;
5) register database;
What is the difference between physical and logical backups?
In Oracle Logical Backup is “which is taken using either Traditional Export/Import or Latest Data Pump”. Where as Physical backup is known “when you take Physical O/s Database related Files as Backup”.
What is RAID? What is RAID0? What is RAID1? What is RAID 10?
RAID: It is a redundant array of independent disk
RAID0: Concatenation and stripping
RAID1: Mirroring
How to enable Fast Incremental Backup to backup only those data blocks that have changed?
SQL> ALTER DATABASE enable BLOCK CHANGE TRACKING;
How do you set the flash recovery area?
SQL> ALTER SYSTEM SET db_recovery_file_dest_size = 100G;
SQL> ALTER SYSTEM SET db_recovery_file_dest = ‘/u10/oradata/school’;
What is auxiliary channel in RMAN? When do you need this?
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.
How do you use the V$RECOVERY_FILE_DEST view to display information regarding the flashrecovery area?
SQL> SELECT name, space_limit, space_used,space_reclaimable, number_of_filesFROM v$recovery_file_dest;
How can you display warning messages?
SQL> SELECT object_type, message_type,message_level, reason, suggested_actionFROM dba_outstanding_alerts;
How do you backup the entire database?
RMAN> BACKUP DATABASE;
How do you backup an individual tablespaces?
RMAN> CONFIGURE DEFAULT DEVICE TYPE TO DISK;
RMAN> BACKUP TABLESPACE system;
How do you backup datafiles and control files?
RMAN> BACKUP DATAFILE 3;
RMAN> BACKUP CURRENT CONTROLFILE;
Use a fast recovery without restoring all backups from their backup location to the location specified inthe controlfile.
RMAN> SWITCH DATABASE TO COPY;
My Database has Level 1 backup, tell me what are all backed up ? with Example?
Database is UP and has taken Level 0 backup, is the backup taken is Consistent or Inconsistent?
How do you say a backup is Consistent or Inconsistent, Oracle Terminology?
Can we take backup when the Database is down?
If i have a RMAN full backup Level 0 of Sun @9PM, on Mon 9PM taken incremental Level 1 backup.What type of backup do you get and what is actually backedup?
If i have a RMAN full backup of Sun @9PM, on Mon 9PM taken incremental Level 1 backup.On Tuesday Database Crashed.What type of backup do you get and what is actually backedup?
There is no Backup available, Can we take a Level 1 backup?
A table got dropped between 9AM - 11AM how to get the Table backup using RMAN,
DB size 500GB available mount point space for table recovery is 15GB?
Sys Admin has changed the time from 10:00 AM to 9:30 AM, table dropped, How do you recover the Table?
A DATAFILE is corrupted and there is no backup, How to recover the datafile?
All Controlfiles are corrupted, How to recover the controlfile?
Restoring means copying the database object from the backup media to the destination where actually it is required where as recovery means to apply the database object copied earlier (roll forward) in order to bring the database into consistent state.
What is the difference between complete and incomplete recovery?
An incomplete database recovery is a recovery that it does not reach to the point of failure. The recovery can be either point of time or particular SCN or Particular archive log specially incase of missing archive log or redolog failure where as a complete recovery recovers to the point of failure possibly when having all archive log backup.
How would you decide your backup strategy and timing for backup?
In fact backup strategy is purely depends upon your organization business need.
If no downtime then database must be run on archivelog mode and you have to take frequently or daily backup.
If sufficient downtime is there and loss of data would not affect your business then you can run your database in noarchivelog mode and backup can be taken in-frequently or weekly or monthly.
In most of the case in an organization when no downtime then frequent inconsistent backup needed (daily backup), multiplex online redo log files (multiple copies), different location for redo log files, database must run in archivelog mode and dataguard can be implemented for extra bit of protection.
What is the benefit of running the DB in archivelog mode over no archivelog mode?
When a database is in no archivelog mode whenever log switch happens there will be a loss of some redoes log information in order to avoid this, redo logs must be archived. This can be achieved by configuring the database in archivelog mode.
If an oracle database is crashed? How would you recover that transaction which is not in backup?
If the database is in archivelog we can recover that transaction otherwise we cannot recover that transaction which is not in backup.
What is the difference between HOTBACKUP and RMAN backup?
For hotbackup we have to put database in begin backup mode, then take backup where as RMAN would not put database in begin backup mode. RMAN is faster can perform incremental (changes only) backup, and does not place tablespace in hotbackup mode.
Can we use Same target database as Catalog database?
No, the recovery catalog should not reside in the target database (database to be backed up) because the database can not be recovered in the mounted state.
Incremental backup levels:
Level 0 – full backup that can be used for subsequent incrementals
RMAN> backup incremental level 0 database;
Differential Level 1–only the blocks that have changed since the last backup (whether it is level 0 or level 1)
RMAN> backup incremental level 1 differential database;
Cumulative Level 1 – all changes since the last level 0 incremental backup
RMAN> backup incremental level 1 cumulative database;
A full backup cannot be used for a cumulative level 1 backup.
A cumulative level 1 backup must be done on top of an incremental level 0 backup.
Why RMAN incremental backup fails even though full backup exists?
If you have taken the RMAN full backup using the command ‘Backup database’, where as a level 0 backup is physically identical to a full backup. The only difference is that the level 0 backup is recorded as an incremental backup in the RMAN repository so it can be used as the parent for a level 1 backup. Simply the ‘full backup without level 0’ can not be considered as a parent backup from which you can take level 1 backup.
Can we perform RMAN level 1 backup without level 0?
If no level 0 is available, then the behavior depends upon the compatibility mode setting (oracle version).
If the compatibility mode less than 10.0.0, RMAN generates a level 0 backup of files contents at the time of backup.
If the compatibility is greater than 10.0.0, RMAN copies all block changes since the file was created, and stores the results as level 1 backup.
How to put Manual/User managed backup in RMAN?
In case of recovery catalog, you can put by using catalog command:
RMAN> CATALOG START WITH ‘/oracle/backup.ctl’;
How to check RMAN version in oracle?
If you want to check RMAN catalog version then use the below query from SQL*plus
SQL> Select * from rcver;
What happens actually in case of instance Recovery?
While Oracle instance fails, Oracle performs an Instance Recovery when the associated database is being re-started. Instance recovery occurs in 2 steps:
Cache recovery: Changes being made to a database are recorded in the database buffer cache as well as redo log files simultaneously. When there are enough data in the database buffer cache, they are written to data files. If an Oracle instance fails before these data are written to data files, Oracle uses online redo log files to recover the lost data when the associated database is re-started. This process is called cache recovery.
Transaction recovery: When a transaction modifies data in a database (the before image of the modified data is stored in an undo segment which is used to restore the original values in case the transaction is rolled back). At the time of an instance failure, the database may have uncommitted transactions. It is possible that changes made by these uncommitted transactions have gotten saved in data files. To maintain read consistency, Oracle rolls back all uncommitted transactions when the associated database is re-started. Oracle uses the undo data stored in undo segments to accomplish this. This process is called transaction recovery.
What is RMAN?
Recovery Manager (RMAN) is a utility that can manage your entire Oracle backup and recovery activities.
What is the difference between using recovery catalog and control file?
When new incarnation happens, the old backup information in control file will be lost. It will be preserved in recovery catalog.
In recovery catalog we can store scripts.
Recovery catalog is central and can have information of many databases.
Can we use same target database as catalog?
No, The recovery catalog should not reside in the target database (database should be backed up), because the database can’t be recovered in the mounted state.
How do you know that how much RMAN task has been completed?
By querying v$rman_status or v$session_longops
From where list & report commands will get input?
Both the commands command quering v$ and recovery catalog views. V$BACKUP_FILES or many of the recovery catalog views such asRC_DATAFILE_COPY or RC_ARCHIVED_LOG.
Command to delete archive logs older than 7days?
RMAN> delete archivelog all completed before sysdate-7;
How many times does oracle ask before dropping a catalog?
The default is two times one for the actual command, the other for confirmation.
How to view the current defaults for the database.
RMAN> show all;
What is the use of crosscheck command in RMAN?
Crosscheck will be useful to check whether the catalog information is intact with OS level information. This command only updates repository records with the status of the backups.
e.g. If user removes archived logs from disk with an operating system command, the repository still indicates that the logs are on disk, when in fact they are not.
What are the differences between crosscheck and validate commands?
Validate command is to examine a backup set and report whether it can be restored. RMAN scans all of the backup pieces in the specified backup sets and looks at the checksum to verify that the contents are intact so that backup can be successfully restored if necessary.
Crosscheck command is to verify the status of backups and copies recorded in the RMAN repository against media such as disk or tape. The crosscheck command only processes files created on the same device type as the channel running crosscheck.
Which one is good, differential (incremental) backup or cumulative (incremental) backup?
A differential backup, which backs up all blocks changed after the most recent incremental backup at level 1 or 0
RMAN> BACKUP INCREMENTAL LEVEL 1 DATABASE;
A cumulative backup, which backs up all blocks changed after the most recent incremental backup at level 0
RMAN> BACKUP INCREMENTAL LEVEL 1 CUMULATIVE DATABASE;
Cumulative backups are preferable to differential backups when recovery time is more important than disk space, because during recovery each differential backup must be applied in succession. Use cumulative incremental backups instead of differential, if enough disk space is available to store cumulative incremental backups.
This is command for taking Level 0 backup.
RMAN> BACKUP INCREMENTAL LEVEL 0 DATABASE;
What is the difference between backup set and backup piece?
Backup set is logical and backup piece is physical.
RMAN command to backup for creating standby database
RMAN> duplicate target database
You loss one datafile and DB is running in ARCHIVELOG mode. You have full database backup of 1 week/day old and don’t have backup of this (newly created) datafile. How do you restore/recover file?
Create data file and recover datafile.
SQL> alter database create datafile ‘/u01/app/oracle/oradata/xyz.dbf’ size 2G;
RMAN> recover datafile file_id;
What is obsolete backup & expired backup?
A status of “expired” means that the backup piece or backup set is not found in the backup destination.
A status of “obsolete” means 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.
What is the difference between hot backup & RMAN backup?
For hot backup, we have to put database in begin backup mode, then take backup.
RMAN won’t put database in backup mode.
How to put manual/user-managed backup in RMAN (recovery catalog)?
By using catalog command.
RMAN> CATALOG START WITH ‘/tmp/backup.ctl’;
What are the Architectural components of RMAN?
RMAN Executables
Sercer process
Channels
Target database
Recovery catalog database (optional)
Media management Layer (optional)
Backups, backup sets and backup pieces
What are channels?
A channel is an RMAN server process started when there is a need to communicate with an I/O device, such as a disk or a tape. A channel is what reads and writes RMAN backup files. It is through the allocation of channels that you govern I/O characteristics:
Type of I/O device being read or written to, either a disk or an sbt_tape
Number of processes simultaneously accessing an I/O device
Maximize size of files created on I/O devices
Maximize rate at which database files are read
Maximize number of files open at a time
Why is the catalog optional?
Because RMAN manages backup and recovery operations, it requires a place to store necessary information about the database. RMAN always stores this information in the target database control file. You can also store RMAN metadata in a recovery catalog schema contained in a separate database. The recovery catalog schema must be stored in a database other than the target database.
What is a Backup set?
A logical grouping of backup files — the backup pieces — that are created when you issue an RMAN backup command. A backup set is RMAN’s name for a collection of files associated with a backup. A backup set is composed of one or more backup pieces.
What are the benefits of using RMAN?
Incremental backups that only copy data blocks that have changed since the last backup.
Tablespaces are not put in backup mode, thus there is noextra redo log generation during online backups.
Detection of corrupt blocks during backups.
Parallelization of I/O operations.
Automatic logging of all backup and recovery operations.
Built-in reporting and listing commands.
What are the various reports available with RMAN
RMAN>list backup;
RMAN> list archive;
In catalog database, if some of the blocks are corrupted due to system crash, How will you recover?
using RMAN BLOCK RECOVER command
How do you enable the autobackup for the controlfile using RMAN?
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
2> ‘$HOME/BACKUP/RMAN/ F.bkp’;
How do you identify what are the all the target databases that are being backed-up with RMAN database?
You don’t have any view to identify whether it is backed up or not. The only option is connect to the target database and give list backup this will give you the backup information with date and timing.
How do you identify the block corruption in RMAN database? How do you fix it?
Using v$block_corruption view you can find which blocks corrupted.
RMAN> block recover datafile <fileid> block <blockid>;
Using the above statement You recover the corrupted blocks. First check whether the block is corrupted or not by using this command
SQL>select file# block# from v$database_block_corruption;
file# block
2 507
the above block is corrupted…
conn to Rman
To recover the block use this command…
RMAN>blockrecover datafile 2 block 507;
the above command recover the block 507
Now just verify it…..
Rman>blockrecover corruption list;
How do you clone the database using RMAN software? Give brief steps? When do you use crosscheck command?
Check whether backup pieces proxy copies or disk copies still exist.
Two commands available in RMAN to clone database:
1) Duplicate
2) Restore.
List some of the RMAN catalog view names which contain the catalog information?
RC_DATABASE_INCARNATION RC_BACKUP_COPY_DETAILS
RC_BACKUP_CORRUPTION
RC_BACKUP-DATAFILE_SUMMARY
How do you install the RMAN recovery catalog?
Steps to be followed:
1) Create connection string at catalog database.
2) At catalog database create one new user or use existing user and give that user a recovery_catalog_owner privilege.
3) Login into RMAN with connection string
a) export ORACLE_SID
b) rman target catalog @connection string
4) rman> create catalog;
5) register database;
What is the difference between physical and logical backups?
In Oracle Logical Backup is “which is taken using either Traditional Export/Import or Latest Data Pump”. Where as Physical backup is known “when you take Physical O/s Database related Files as Backup”.
What is RAID? What is RAID0? What is RAID1? What is RAID 10?
RAID: It is a redundant array of independent disk
RAID0: Concatenation and stripping
RAID1: Mirroring
How to enable Fast Incremental Backup to backup only those data blocks that have changed?
SQL> ALTER DATABASE enable BLOCK CHANGE TRACKING;
How do you set the flash recovery area?
SQL> ALTER SYSTEM SET db_recovery_file_dest_size = 100G;
SQL> ALTER SYSTEM SET db_recovery_file_dest = ‘/u10/oradata/school’;
What is auxiliary channel in RMAN? When do you need this?
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.
How do you use the V$RECOVERY_FILE_DEST view to display information regarding the flashrecovery area?
SQL> SELECT name, space_limit, space_used,space_reclaimable, number_of_filesFROM v$recovery_file_dest;
How can you display warning messages?
SQL> SELECT object_type, message_type,message_level, reason, suggested_actionFROM dba_outstanding_alerts;
How do you backup the entire database?
RMAN> BACKUP DATABASE;
How do you backup an individual tablespaces?
RMAN> CONFIGURE DEFAULT DEVICE TYPE TO DISK;
RMAN> BACKUP TABLESPACE system;
How do you backup datafiles and control files?
RMAN> BACKUP DATAFILE 3;
RMAN> BACKUP CURRENT CONTROLFILE;
Use a fast recovery without restoring all backups from their backup location to the location specified inthe controlfile.
RMAN> SWITCH DATABASE TO COPY;
My Database has Level 1 backup, tell me what are all backed up ? with Example?
Database is UP and has taken Level 0 backup, is the backup taken is Consistent or Inconsistent?
How do you say a backup is Consistent or Inconsistent, Oracle Terminology?
Can we take backup when the Database is down?
If i have a RMAN full backup Level 0 of Sun @9PM, on Mon 9PM taken incremental Level 1 backup.What type of backup do you get and what is actually backedup?
If i have a RMAN full backup of Sun @9PM, on Mon 9PM taken incremental Level 1 backup.On Tuesday Database Crashed.What type of backup do you get and what is actually backedup?
There is no Backup available, Can we take a Level 1 backup?
A table got dropped between 9AM - 11AM how to get the Table backup using RMAN,
DB size 500GB available mount point space for table recovery is 15GB?
Sys Admin has changed the time from 10:00 AM to 9:30 AM, table dropped, How do you recover the Table?
A DATAFILE is corrupted and there is no backup, How to recover the datafile?
All Controlfiles are corrupted, How to recover the controlfile?
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