Home > Articles > Data > DB2

  • Print
  • + Share This
This chapter is from the book

Answers

Question 1

The correct answer is D. If you are concerned about running out of log space and you want to avoid allocating a large number of secondary log files, you can configure a database to perform infinite logging. To enable infinite logging, you simply set the database configuration parameters userexit and logsecond to ON and –1, respectively.

Question 2

The correct answer is A. If the logretain configuration parameter for a database is set to RECOVERY and/or the userexit parameter is set to YES, archival logging is used and roll-forward recovery operations can be performed against the database. On the other hand, when both of these configuration parameters are set to NO, which is the default, circular logging is used and roll-forward recovery is not supported. In either case, crash recovery is supported.

Question 3

The correct answer is B. Whenever transaction processing is interrupted by an unexpected event (such as a power failure), the database the transaction was interacting with at the time is placed in an inconsistent state. Such a database will remain in an inconsistent state and will be unusable until a crash recovery operation returns it to some point of consistency; an inconsistent database will notify users and applications that it is unusable via a return code and error message that is generated each time an attempt to establish a connection to it is made. In such a case, crash recovery can be initiated by executing the RESTART command. (Had the autorestart database configuration parameter been set to ON, a crash recovery operation would have been started automatically when the user attempted to connect to the SAMPLE database and the error message would not have been displayed.)

Question 4

The correct answer is B. If the indexrec parameter of a database's configuration file is set to RESTART, invalid indexes will be rebuilt, either explicitly or implicitly, when the database is restarted (i.e., when crash recovery is performed on the database) and it will take longer to restart the database. On the other hand, if the indexrec parameter is set to ACCESS, invalid indexes will be rebuilt the first time they are accessed (after they have been marked as being invalid) and users may experience a decrease in performance.

Question 5

The correct answer is B. The purpose of a redirected restore (which is initiated by executing the RESTORE command with the REDIRECT option specified) is to redefine any invalid tablespace containers encountered at the beginning of the recovery process. (The TO [Location] option of the RESTORE command is used to restore a database to a location that is different from its original location and it's impossible to change tablespace types with a restore operation, or any other operation for that matter.)

Question 6

The correct answers are C and D. Because the logretain database configuration parameter has been set to YES, roll-forward recovery has been enabled for the SAMPLE database. As a result, when the database is restored using the RESTORE command, it will automatically be placed in "Roll-forward pending" state. While the database is in "Roll-forward pending" state, it cannot be accessed by users and applications. And the only way a database can be taken out of "Roll-forward pending" state is by executing the ROLLFORWARD command with either the STOP or the COMPLETE option specified.

Question 7

The correct answer is C. If the BUFFER option of the RESTORE command is not used to specify how much buffer space should be reserved for the RESTORE utility, the amount of buffer space used is determined by the value of the restbufsz DB2 Database Manager configuration parameter. (Likewise, if the BUFFER option of the BACKUP command is not used to specify how much buffer space should be reserved for the BACKUP utility, the amount of buffer space used is determined by the value of the backbufsz DB2 Database Manager configuration parameter.)

Question 8

The correct answer is B. Infinite logging is enabled by setting the userexit database configuration parameter to YES and the logsecond database configuration parameter to –1.

Question 9

The correct answer is D. If the logretain configuration parameter for a database is set to RECOVERY and/or the userexit parameter is set to YES, archival logging is used, roll-forward recovery operations can be performed against the database, and the database is considered to be recoverable. On the other hand, when both of these configuration parameters are set to NO, circular logging is used, roll-forward recovery is not supported, and the database is considered to be non-recoverable.

Question 10

The correct answer is A. An online archive log file is a log file that contains records that are associated with completed transactions that resides in the active log directory. As soon as an online archive log file is moved from the active log directory to another storage location, it becomes an offline archive log file.

Question 11

The correct answer is B. Unless the ROLLFORWARD command is executed with the USING LOCAL TIME option, all time values are assumed to be Coordinated Universal Time (also referred to as Greenwich Mean Time) values.

Question 12

The correct answer is C. To enable log file mirroring (also referred to as dual logging), you simply assign the fully qualified name of the mirror log location to the mirrorlogpath database configuration parameter.

Question 13

The correct answer is C. When executed, the SET WRITE SUSPEND FOR DATABASE command causes the DB2 Database Manager to suspend all write operations to tablespace containers and log files that are associated with the current database. All database operations, apart from online backup and restore operations, will function normally while database writes are suspended. That's because read-only transactions are not suspended and are able to continue working with the suspended database, provided they do not request a resource that is being held by the suspended I/O process. Furthermore, applications can continue to process insert, update, and delete operations using data that has been cached in the database's buffer pool(s). However, new pages cannot be read into the buffer pool(s) and no new database connections can be established.

Question 14

The correct answer is D. An incremental backup is a backup image that only contains pages that have been updated since the previous backup image was made. Along with updated data and index pages, each incremental backup image also contains all of the initial database meta-data (such as database configuration, tablespace definitions, recovery history file, etc.) that is normally found in full backup images.

Question 15

The correct answer is A. Information about backup operations is recorded in a database's recovery history file and you can view the contents of a recovery history file by executing the LIST HISTORY command. The proper syntax for listing just backup operation information with the LIST HISTORY command is LIST HISTORY BACKUP ALL FOR [DatabaseName].

Question 16

The correct answer is C. When a recoverable database is restored from a backup image, it is automatically placed in "Roll-forward pending" state unless the WITHOUT ROLLING FORWARD option is used with the RESTORE command. Because the backup image was made while the database was offline, no changes were made between 1:00 AM and 2:30 AM. Therefore, by restoring the database from the backup image that was taken at 1:00 AM and by specifying the WITHOUT ROLLING FORWARD option, the database will be returned to the state it was in at 2:30 AM and it will be taken out of "Roll-forward pending" state.

  • + Share This
  • 🔖 Save To Your Account