# OCA: Oracle Database 11g Administrator Certified Associate- P22

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## OCA: Oracle Database 11g Administrator Certified Associate- P22

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## Nội dung Text: OCA: Oracle Database 11g Administrator Certified Associate- P22

1. Exam Essentials 881 Know how flashback database option works. The flashback database option can greatly reduce the time required to rewind the database to a prior point in time. Understand the parameters associated with flashback database. Understand backup catalog maintenance. Show how the EM Database Control interface simplifies cataloging, crosschecking, and cleaning up.
2. 882 Chapter 15 N Implementing Database Backups Review Questions 1. Among the failure events, which is the most serious? A. The loss of an entire redo log file group but no loss in any other group B. The loss of one member of each redo log file group C. The failure of the ARC0 background process D. The failure of the LGWR background process 2. To enable the flashback database option, the database must be in which of the following modes? A. NOARCHIVELOG mode B. ARCHIVELOG mode C. FLASHBACK LOG mode D. BEGIN BACKUP mode 3. When the database is in ARCHIVELOG mode, database recovery is possible up to which event or time? A. The last redo log file switch B. The last checkpoint position C. The last commit D. The last incremental backup using RMAN 4. From the following, choose the true statement regarding image copies and backup sets. A. An image copy stores one data file per image copy, and a backup set can store all data files in a single file. B. An image copy stores one data file per image copy, and a backup set consists of one file per data file backed up. C. Both image copies and backup sets use a single file to store all objects to be backed up. D. A backup set stores each data file in its own backup file, but an image copy places all data files into a single output file. 5. The option on the EM Database Control backup-scheduling options screen that allows you to refresh an image copy on disk with an incremental backup is known as which RMAN feature? A. Incrementally updated backups B. Incremental level-zero backups C. Compressed image-copy refresh D. Compressed incremental backups
3. Review Questions 883 6. When should the DBA make a trace copy of the control file using ALTER DATABASE BACKUP CONTROLFILE TO TRACE? A. After every backup B. After multiplexing the control files C. Whenever restarting the instance D. Whenever the physical structure of the database changes 7. Which of the following is not a step in configuring your database to archive redo log files? A. Place the database in ARCHIVELOG mode. B. Multiplex the online redo log files. C. Specify a destination for archived redo log files. D. Specify a naming convention for your archived redo log files. 8. Why are online backups known as inconsistent backups? A. Because not all control files are synchronized to the same SCN until the database is shut down B. Because both committed and uncommitted transactions are included in a backup when the database is online C. Because a database failure while an online backup is in progress can leave the database in an inconsistent state D. Because online backups make copies of data files while they are not consistent with the control files 9. Which parameter is used to specify the archive-log destination? A. ARCHIVE_LOG_DEST_n B. LOG_ARCHIVE_DEST_n C. DB_CREATE_FILE_DEST D. DB_RECOVERY_FILE_DEST_n 10. Which of the following initialization parameters specifies the location where the control file trace backup is sent? A. DIAGNOSTIC_DEST B. BACKGROUND_DUMP_DEST C. LOG_ARCHIVE_DEST D. CORE_DUMP_DEST 11. Which of the following pieces of information is not available in the control file? A. Instance name B. Database name C. Tablespace names D. Log sequence number
4. 884 Chapter 15 N Implementing Database Backups 12. Which data dictionary view shows that the database is in ARCHIVELOG mode? A. V$INSTANCE B. V$LOG C. V$DATABASE D. V$THREAD 13. Which file records all changes made to the database and is used only when recovering an instance? A. Archive-log file B. Redo log file C. Control file D. Alert log file 14. Which initialization parameter contains the value used as the default for archived log file destination 10? A. LOG_ARCHIVE_DEST B. STANDBY_ARCHIVE_DEST C. LOG_ARCHIVE_DUPLEX_DEST D. DB_RECOVERY_FILE_DEST E. USE_DB_RECOVERY_FILE_DEST 15. Which of the following commands is a key step in multiplexing control files using an spfile? A. ALTER SYSTEM SET CONTROL_FILES= ‘/u01/oradata/PRD/cntrl01.ctl’, ‘/u01/ oradata/PRD/cntrl02.ctl’ SCOPE=SPFILE; B. ALTER SYSTEM SET CONTROL_FILES= ‘/u01/oradata/PRD/cntrl01.ctl’, ‘/u01/ oradata/PRD/cntrl02.ctl’ SCOPE=MEMORY; C. ALTER SYSTEM SET CONTROL_FILES= ‘/u01/oradata/PRD/cntrl01.ctl’, ‘/u01/ oradata/PRD/cntrl02.ctl’ SCOPE=BOTH; D. The number of control files is fixed when the database is created. 16. Which statement adds a member /logs/redo22.log to redo log file group 2? A. ALTER DATABASE ADD LOGFILE ‘/logs/redo22.log’ TO GROUP 2; B. ALTER DATABASE ADD LOGFILE MEMBER ‘/logs/redo22.log’ TO GROUP 2; C. ALTER DATABASE ADD MEMBER ‘/logs/redo22.log’ TO GROUP 2; D. ALTER DATABASE ADD LOGFILE ‘/logs/redo22.log’; 17. What is the biggest advantage of having the control files on different disks? A. Database performance. B. Guards against failure. C. Faster archiving. D. Writes are concurrent, so having control files on different disks speeds up control file writes.
5. Review Questions 885 18. To place the database into ARCHIVELOG mode, in which state must you start the database? A. MOUNT B. NOMOUNT C. OPEN D. SHUTDOWN E. Any of the above 19. Which of the following commands places the database in ARCHIVELOG mode? A. ALTER SYSTEM ARCHIVELOG; B. ALTER DATABASE ARCHIVELOG; C. ALTER SYSTEM SET ARCHIVELOG=TRUE; D. ALTER DATABASE ENABLE ARCHIVELOG MODE; E. ALTER DATABASE ARCHIVELOG MODE; 20. Which of the following substitution-variable formats are always required for specifying the names of the archived redo log files? (Choose all that apply.) A. %d B. %s C. %r D. %t
6. 886 Chapter 15 N Implementing Database Backups Answers to Review Questions 1. A. Losing an entire redo log file group can result in losing committed transactions that may not yet have been written to the database files. Losing all members of a redo log file group except for one does not affect database operation and does not result in lost data. A mes- sage is placed in the alert log file. The failure of LGWR or ARC0 causes an instance failure, but you do not lose any committed transaction data. 2. B. To enable the flashback database option, the database must be in ARCHIVELOG mode. FLASHBACK LOG mode is not a valid mode of database operation. BEGIN BACKUP mode is used to perform hot backups without using RMAN. 3. C. In ARCHIVELOG mode, recovering the database is possible up to the last COMMIT state- ment; in other words, no committed transactions are lost in ARCHIVELOG mode. 4. A. Image copies are duplicate data and log files in OS format. Backup sets are binary com- pressed files in Oracle proprietary format. In addition to storing multiple data files in a single output file, backup sets do not contain unused blocks. 5. A. Incrementally updated backups save time during a recovery operation because fewer incremental backups need to be applied to the restored image copy. 6. D. In the rare event that all multiplexed copies of the control file are lost, having a trace copy of the control file reduces the possibility of data loss and reduces downtime during a recovery operation. The preferred and recommended way to back up a control file is to enable control file autobackup using RMAN. 7. B. Although it is recommended that you multiplex your online redo log files, it is not required to enable ARCHIVELOG mode of the database. 8. D. During an online backup, even if all data files are backed up at the same time, they are rarely, if ever, in sync with the control file. 9. B. LOG_ARCHIVE_DEST_n specifies the archive-log location. You can configure up to 10 archive-log destinations. LOG_ARCHIVE_DEST_10 is reserved for the flash recovery area, which is specified by the parameter DB_RECOVERY_FILE_DEST. 10. A. The trace backup is created in a subdirectory under the location specified by the DIAGNOSTIC_DEST parameter—$DIAGNOSTIC_DEST/diag/// trace directory. 11. A. The instance name is not in the control file. The control file has information about the physical database structure. 12. C. The V$DATABASE view in the column LOG_MODE shows whether the database is in ARCHIVELOG mode or in NOARCHIVELOG mode. 13. B. The redo log file records all changes made to the database. The LGWR process writes the redo log buffer entries to the redo log files. These entries are used to roll forward, or to update, the data files during an instance recovery. Archive log files are used for media recovery.
7. Answers to Review Questions 887 14. D. DB_RECOVERY_FILE_DEST points to the flash recovery area, and this is the default for archived log-file destination number 10. 15. A. The location of the new control files is not valid until an operating-system copy is made of the current control file to the new location(s) and the instance is restarted. The SCOPE=SPFILE option specifies that the parameter change will not take place until a restart. Specifying either MEMORY or BOTH causes an error, because CONTROL_FILES is not a dynamic parameter. 16. B. When adding log-file members, specify the group number, or specify all the existing group members. 17. B. Having the control files on different disks ensures that even if you lose one disk, you lose only one control file. If you lose one of the control files, you can shut down the database and copy a control file, or you can change the CONTROL_FILES parameter and restart the database. 18. A. To put the database into ARCHIVELOG mode, the database must be in the MOUNT state; the control files and all data files that are not offline must be available to change the database to ARCHIVELOG mode. 19. B. You use the ALTER DATABASE ARCHIVELOG command while the database is in the MOUNT state to enable archiving of online redo log files. 20. B, C, D. The substitution variable %d, which represents the database ID, is required only if multiple databases share the same archive-log destination.
8. Chapter Recovering the 16 Database ORacle Database 11g: aDministRatiOn i exam Objectives cOveReD in this chapteR: Backup and Recovery Concepts ÛÛ NÛ Identify the types of failure that can occur in an Oracle database NÛ Describe ways to tune instance recovery Performing Database Recovery ÛÛ NÛ Overview of Data Recovery Advisor NÛ Use Data Recovery Advisor to Perform recovery (Control file, Redo log file, and Data file)
15. 896 Chapter 16 N Recovering the Database ORA-01157: cannot identify/lock data file 4 - see DBWR trace file ORA-01110: data file 4: ‘/u05/oradata/ord/users01.dbf’ SQL> The message in SQL*Plus shows only the first data file that needs attention. You will have to use the dynamic performance view V$RECOVER_FILE to list all the files that need attention. Here is a query against the view V$RECOVER_FILE and a second query joining V$RECOVER_FILE and V$DATAFILE given the previous STARTUP command: SQL> select file#, error from v$recover_file; FILE# ERROR ---------- --------------------------------------------- 4 FILE NOT FOUND 11 FILE NOT FOUND SQL> select file#, name from 2 v$datafile join v\$recover_file using (file#); FILE# NAME ---------- ---------------------------------------- 4 /u05/oradata/ord/users01.dbf 11 /u08/oradata/ord/idx02.dbf SQL> If a data file is offline or taken offline, the instance can still start as long as the data file does not belong to the SYSTEM or UNDO tablespace. Once the instance is started, you can proceed to recover the missing or corrupted data file and subsequently bring it online. If all files are available but out of sync, automatic instance recovery is performed as long as the online redo log files can bring all data files to the same SCN. Otherwise, media recovery is required using archived redo log files. If a redo log group member is missing, a message is generated in the alert log, but the database will still open. Keeping an Instance from Failing Media failures are not always critical, depending on which type of data file is lost. If any of the multiplexed copies of the control file are lost, an entire redo log group is lost, or any data file from the SYSTEM or UNDO tablespace is lost, the instance will fail. In some cases, the instance becomes unavailable to users but will not shut down; in this case, you can use SHUTDOWN ABORT to force the instance to shut down without resynchroniz- ing the data files with the control file. The next time the instance is started, instance recov-