Q&As: Hot Backups

(Q) Which statements about Open (hot/online) database backups are correct?

• ( ) To perform HOT backups, the database MUST be in ARCHIVELOG mode
• ( ) To perform a user-managed HOT backup, you MUST use BEGIN Backup.... END Backup.
• ( ) You CAN perform closed database backups using RMAN.
• ( ) You CAN run a Data Pump Export to perform a CONSISTENT LOGICAL backup of the database.
• ( ) INCREMENTAL backups are supported, using RMAN.

Q&As: Fast Recovery Area (I)

(Q) What is a Fast Recovery Area? What does it contain?

• Is an Oracle managed space that can be used to hold RMAN disk backups, control file autobackups, and archived redo logs
• Files here are maintained by Oracle and have an OMF format
• Disk location in which the database can store and manage files related to backup and recovery. It contains:

(a) multiplexed copies of current control file and online redo logs, (b) archived redo logs (c) Foreign archived redo logs (d) flashback logs (e) image copies of datafiles and control files (f) backup pieces

(Q) What does Oracle recommends about the location of the Fast Recovery Area?

• Should be on a separate disk from the database area (database files, control file, redo logs)
• DB_RECOVERY_FILE_DEST should be different than DB_CREATE_FILE_DEST or any DB_CREATE_ONLINE_LOG_DEST_n

(Q) How can you find out the size of the Fast Recovery Area?

SQL> show parameter db_recovery

NAME        TYPE  VALUE
---------------------------- ----------- ------------------------------
db_recovery_file_dest      string  /u01/app/oracle/flash_recovery_area
db_recovery_file_dest_size   big integer 4977M

(Q) What is the default size of an online log created in the Fast Recovery Area?

• 100 Mb

(Q) Which statements about Fast Recovery Area are correct?

• ( ) Fast Recovery Area automates management of backup-related files.
• ( ) It minimizes the need to manually manage disk space for backup-related files
• ( ) It balances the use of space among the different types of files
• ( ) When you create a Fast recovery area:

(a) you choose a location on disk and set an upper bound for storage space. (b) you set a backup retention policy

• ( ) RMAN retains the data file backups required to satisfy the current retention policy AND any arquived redo logs required for complete recovery of those data file backups

Q&As: Cold database backups

(Q) Which statements about Closed (cold/offline) database backups are correct?

• ( ) You CAN perform closed database backups using RMAN.
• ( ) To perform closed db backups with RMAN, the instance MUST be MOUNTED
• ( ) You CAN perform user-managed closed database backups (OFFLINE backups), following the steps below:
• Run shell script to collect location of all datafiles, control files, redo log files, and parameter files
• If using server parameter file, run command to backup spfile
• Shutdown the database normal or immediate
• Run OS script to copy all datafiles, control files, redo logs and parameter files to backup area
• Startup the database
• ( ) You CANNOT run a Data Pump Export on a closed database.

Q&As: Block Media Recovery

(Q) What is Block Media Recovery?

Recovery of specified blocks within a data file
RMAN> RECOVER ... BLOCK
Leaves the affected datafiles ONLINE and recovers only the damaged/corrupted data blocks.

$ rman
RMAN> connect target /
connected to target database: ORCL11G (DBID=123456789)

RMAN> recover datafile 2 block 13;
...

     (optionally)
RMAN> recover … 
        From backupset …
        Exclude flashback log

     (To recover ALL blocks logged in V$DATABASE_BLOCK_CORRUPTION)
RMAN> recover corruption list;

Q&As: Fast Recovery Area (II)

(Q) What initialization parameters are used to configure a Fast Recovery Area?

• DB_RECOVERY_FILE_DEST - specifies default location for fast recovery area.
• DB_RECOVERY_FILE_DEST_SIZE - specifies (in bytes) the hard limit on the total space to be used by target database recovery files created in the fast recovery area
• (optional) DB_FLASHBACK_RETENTION_TARGET -Specifies the upper limit (minutes) on how far back in time the database may be flashed back.

(Q) Can you configure the Fast Recovery Area on an ASM disk group?

• Yes

(Q) How large should you configure the Fast Recovery Area?

• At an ABSOLUTE MINIMUM, it should be large enough to containt the archived redo logs not yet on tape.
• Scenario:
• If you use incrementally updated backups and set the backup retention policy to REDUNDANCY 1, you can determine the size of the fast recovery area as below: