Oracle Oracle Certifications 1Z0-053 Questions & Answers

• Question 371:

  Which of the following are true concerning block media recovery? (Choose all that apply.)

  A. Any gap in archive logs ends the recovery.

  B. If a gap in archive logs is encountered, RMAN will search forward for newer versions of the blocks that are not corrupt.

  C. Uncorrupted blocks from the flashback logs may be used to speed recovery.

  D. The database can be in NOARCHIVELOG mode.

  E. None of the above.

  Correct Answer: BC

  Overview of Block Media Recovery (link)

  Basic Concepts of Block Media Recovery

  Whenever block corruption has been automatically detected, you can perform block media recovery manually with the RECOVER ... BLOCK command. By default, RMAN first searches for good blocks in the real-time query physical standby

  database, then flashback logs and then blocks in full or level 0 incremental backups.

  Prerequisites for Block Media Recovery (link)

  The following prerequisites apply to the RECOVER ... BLOCK command:

  The target database must run in ARCHIVELOG mode and be open or mounted with a current control file.

  If the target database is a standby database, then it must be in a consistent state, recovery cannot be in session, and the backup must be older than the corrupted file.

  The backups of the data files containing the corrupt blocks must be full or level 0 backups and not proxy copies.

  If only proxy copy backups exist, then you can restore them to a nondefault location on disk, in which case RMAN considers them data file copies and searches them for blocks during block media recovery.

  RMAN can use only archived redo logs for the recovery. RMAN cannot use level 1 incremental backups.

  Block media recovery cannot survive a missing or inaccessible archived redo log, although it can sometimes survive missing redo records.

  Flashback Database must be enabled on the target database for RMAN to search the flashback logs for good copies of corrupt blocks. If flashback logging is enabled and contains older, uncorrupted versions of the corrupt blocks, then RMAN

  can use these blocks, possibly speeding up the recovery. The target database must be associated with a real-time query physical standby database for RMAN to search the database for good copies of corrupt blocks.

  Restore Failover (link)

  RMAN automatically uses restore failover to skip corrupted or inaccessible backups and look for usable backups. When a backup is not found, or contains corrupt data, RMAN automatically looks for another backup from which to restore the

  desired files.

• Question 372:

  In what view are you likely to see the following output?

  

  A. V$SESSION_EVENT

  B. V$SESSION

  C. V$WAITS

  D. V$WAITSTAT

  E. V$SYSSTAT

  Correct Answer: B

• Question 373:

  What view might you use to try to determine how long a particular backup will take?

  A. V$SESSION_EVENT

  B. V$SESSION

  C. V$WAITS

  D. V$WAITSTAT

  E. V$SESSION_LONGOPS

  Correct Answer: E

• Question 374:

  The environmental variable ORACLE_BASE is set. You want to check the diagnostic files created as part of the Automatic Diagnostic Repository (ADR). View the Exhibit and note the various parameters set in your database.

  What will be the location of the ADR base?

  Exhibit:

  

  A. It is set to ORACLE_BASE.

  B. It is set to ORACLE_HOME/log.

  C. It is set to /u01/app/oracle/admin/orcl/adump.

  D. It is set to /u01/app/oracle/flash_recovery_area.

  Correct Answer: A

  The ADR root directory is known as ADR base. Its location is set by the DIAGNOSTIC_DEST initialization parameter. If this parameter is omitted or left null, the database sets DIAGNOSTIC_DEST upon startup as follows:

  If environment variable ORACLE_BASE is set, DIAGNOSTIC_DEST is set to the directory designated byORACLE_BASE. If environment variable ORACLE_BASE is not set, DIAGNOSTIC_DEST is set to ORACLE_HOME/log.

• Question 375:

  Which of the following is a prerequisite for running DBMS_TDB.CHECK_DB to a successful completion?

  A. The database must be in read-write mode.

  B. The database must have no external files.

  C. The database must open in read-only mode.

  D. The database must be mounted but not opened.

  Correct Answer: C

• Question 376:

  Which statement is true regarding the retention policy for the incidents accumulated in the Automatic Diagnostic Repository (ADR)?

  A. The incident metadata is purged when the problem is resolved and the DBA closes the SR.

  B. The incident files and dumps are not retained in the ADR for the manually created incidents.

  C. The incident files are retained but the incident metadata is purged when the problem is resolved and the DBA closes the SR

  D. The default setting is for one year after which the incident metadata is purged from the ADR and the files are retained for one month.

  Correct Answer: D

  

• Question 377:

  Which of the following are correct about block media recovery? (Choose all that apply.)

  A. Physical and logical block corruption is recorded automatically in V$DATABASE_BLOCK_CORRUPTION.

  B. Logical corruptions are repairable by BMR.

  C. Physical corruptions are repairable by BMR.

  D. RMAN can use any backup for a BMR restore.

  E. ARCHIVELOG mode is not required if you have both a full and incremental backup for restore.

  Correct Answer: AC

  Overview of Block Media Recovery (link)

  Basic Concepts of Block Media Recovery

  Whenever block corruption has been automatically detected, you can perform block media recovery manually with the RECOVER ... BLOCK command. By default, RMAN first searches for good blocks in the real-time query physical standby

  database, then flashback logs and then blocks in full or level 0 emental backups.

  Identification of Corrupt Blocks

  The V$DATABASE_BLOCK_CORRUPTION view displays blocks marked corrupt by database components such as RMAN, ANALYZE, dbv, and SQL queries. The following types of corruption result in the addition of rows to this view:

  Physical corruption (sometimes called media corruption) The database does not recognize the block: the checksum is invalid, the block contains all zeros, or the block header is corrupt. Physical corruption checking is enabled by default. You

  can turn off checksum checking by specifying the NOCHECKSUM option of the BACKUP command, but other physical consistency checks, such as checks of the block headers and footers, cannot be disabled.

  Logical corruption:

  The block has a valid checksum, the header and footer match, and so on, but the contents are logically inconsistent. Block media recovery may not be able to repair all logical block corruptions. In these cases, alternate recovery methods,

  such as tablespace point-in- time recovery, or dropping and re-creating the affected objects, may repair the corruption. Logical corruption checking is disabled by default. You can turn it on by specifying the CHECK LOGICAL option of the

  BACKUP, RESTORE, RECOVER, and VALIDATE commands.

  The database can detect some corruptions by validating relationships between blocks and segments, but cannot detect them by a check of an individual block. The V DATABASE_BLOCK_CORRUPTION view does not record at this level of

  granularity.

  Prerequisites for Block Media Recovery (link)

  The following prerequisites apply to the RECOVER ... BLOCK command:

  The target database must run in ARCHIVELOG mode and be open or mounted with a current control file.

  If the target database is a standby database, then it must be in a consistent state, recovery cannot be in session, and the backup must be older than the corrupted file.

  The backups of the data files containing the corrupt blocks must be full or level 0 backups and not proxy copies.

  If only proxy copy backups exist, then you can restore them to a nondefault location on disk, in which case RMAN considers them data file copies and searches them for blocks during block media recovery.

  RMAN can use only archived redo logs for the recovery. RMAN cannot use level 1 incremental backups.

  Block media recovery cannot survive a missing or inaccessible archived redo log, although it can sometimes survive missing redo records.

  Flashback Database must be enabled on the target database for RMAN to search the flashback logs for good copies of corrupt blocks. If flashback logging is enabled and contains older, uncorrupted versions of the corrupt blocks, then RMAN

  can use these blocks, possibly speeding up the recovery. The target database must be associated with a real-time query physical standby database for RMAN to search the database for good copies of corrupt blocks.

• Question 378:

  Choose the correct order to package and upload data for an incident to Oracle Support.

  A. Schedule, create new package, view manifest, view contents

  B. Create new package, view manifest, view contents, schedule

  C. Schedule, create new package, view contents, view manifest

  D. Create new package, view contents, view manifest, schedule

  E. None of the above.

  Correct Answer: D

  

• Question 379:

  Which of the following is NOT an advantage of block media recovery (BMR)?

  A. Reduced MTTR.

  B. Datafiles remain offline while corrupt blocks are repaired.

  C. Datafiles remain online while corrupt blocks are repaired.

  D. A and C

  Correct Answer: B

  Overview of Block Media Recovery (link)

  Purpose of Block Media Recovery

  You can use block media recovery to recover one or more corrupt data blocks within a data file. Block media recovery provides the following advantages over data file media recovery:

  Lowers the mean time to recover (MTTR) because only blocks needing recovery are restored and recovered Enables affected data files to remain online during recovery

  Without block media recovery, if even a single block is corrupt, then you must take the data file offline and restore a backup of the data file. You must apply all redo generated for the data file after the backup was created. The entire file is unavailable until media recovery completes. With block media recovery, only the blocks actually being recovered are unavailable during the recovery.

  Block media recovery is most useful for physical corruption problems that involve a small, well- known number of blocks. Block-level data loss usually results from intermittent, random I/O errors that do not cause widespread data loss, and memory corruptions that are written to disk. Block media recovery is not intended for cases where the extent of data loss or corruption is unknown and the entire data file requires recovery. In such cases, data file media recovery is the best solution.

• Question 380:

  Which of the following tasks does the tool Incident Packaging Service (IPS) perform?

  A. Cleans up the ADR by deleting files not associated with an incident uploaded to Oracle Support.

  B. Identifies all files associated with a critical error and adds them to a zip file to be sent to Oracle Support.

  C. Automatically opens a Service Request with Oracle Support for each critical error and sends all relevant files.

  D. Displays a high-level view of critical errors on the database home page.

  Correct Answer: B

  Incident packaging service (IPS) and incident packages The IPS enables you to automatically and easily gather the diagnostic data--traces, dumps, health check reports, and more--pertaining to a critical error and package the data into a zip file for transmission to Oracle Support. Because all diagnostic data relating to a critical error are tagged with that error's incident number, you do not have to search through trace files and other files to determine the files that are required for analysis; the incident packaging service identifies the required files automatically and adds them to the zip file. Before creating the zip file, the IPS first collects diagnostic data into an intermediate logical structure called an incident package (package).

  Packages are stored in the Automatic Diagnostic Repository. If you choose to, you can access this intermediate logical structure, view and modify its contents, add or remove additional diagnostic data at any time, and when you are ready, create the zip file from the package. After these steps are completed, the zip file is ready to be uploaded to Oracle Support.