Question 1

There are other methods of performing consistent backups,such as using export utilities,which by definition are cold backups.

Accepted Answer

Export utilities do not necessarily perform cold backups; they can often be used to perform logical backups while the database is running, which does not require shutting down the database (a characteristic of cold backups).

Question 2

Recovery of a controlfile does not actually involve any kind of recovery process,but rather one of restoration or rebuilding of the controlfile.

Accepted Answer

Recovery of a controlfile involves restoring or rebuilding the controlfile from a backup. It does not involve any kind of recovery process because the controlfile does not contain data that needs to be recovered.

Question 3

Restoration of a recovered backup is a simple process of applying redo log entries to the datafile,until the datafile "catches up" to the time indicated by the archive log.

Accepted Answer

Restoration of a recovered backup involves applying redo log entries to roll forward the database to a specific point in time, but it is the archive logs, not the redo logs, that are applied to the datafiles during this process. Redo logs are used for real-time transaction logging, while archive logs are backups of redo logs used for recovery.

Question 4

The redo log files are typically covered for backups by simply duplexing redo log groups to have multiple members in each group.

Accepted Answer

Duplexing redo log groups by having multiple members in each group provides redundancy and ensures that backups are covered.

Question 5

An abort shutdown of a database,or a power failure,kills all processes and clears all memory buffers immediately,regardless of what is executing in the database.

Accepted Answer

An abort shutdown or power failure will cause an immediate termination of all processes and clear all memory buffers, regardless of their state or what they were executing. This can cause data loss or other issues if proper precautions are not taken to ensure that the database is in a consistent state before the shutdown occurs.

Question 6

OLTP databases are often required to be available on a 24-hour basis.

Accepted Answer

OLTP databases are designed for real-time, transactional processing and are expected to be available 24/7. Organizations depend heavily on these databases to support their day-to-day business operations, so downtime can result in significant financial losses and reputational damage. As a result, OLTP systems often utilize high availability and disaster recovery mechanisms to ensure continuous operation.

Question 7

Copying redo log files from a cold backup back into a database is only necessary when redo log files have been lost.

Accepted Answer

Redo log files contain all the changes made to the database since the last checkpoint, so if they are lost, the database cannot recover transactions that were not yet written to the data files. Therefore, copying them from a cold backup may be necessary to restore the database to a consistent state.

Question 8

Redo log files should be backed up for a hot backup,when the database is completely shut down to provide a snapshot of the entire database.

Accepted Answer

Redo log files should not be backed up when the database is completely shut down as they are only used for recovery purposes in case of a system failure during the operation of the database. For a hot backup, redo log files should be backed up while the database is still running to ensure all changes are captured.

Question 9

Archive log files contain older records of transactions performed in the database.

Accepted Answer

Archive log files are backups of the redo log files which contain the history of all changes made to the database. These files are used to recover the database in case of a failure.

Question 10

You should never multiplex controlfiles.

Accepted Answer

Multiplexing controlfiles is a recommended practice in order to provide redundancy and avoid a single point of failure.

Question 11

A hot backup takes a snapshot of the entire physical structure of a database (all the datafiles,controlfiles,redo logs,and archive logs);if the database is not shut down,and any changes are made during the copy process,an inconsistent backup will result.

Accepted Answer

A hot backup, also known as an online backup, allows the database to remain open and available for use while the backup is occurring. It captures the state of the database at a point in time, including all necessary files to ensure a consistent state can be restored. Changes made during the backup process are tracked and included to ensure consistency.

Question 12

Restoration can utilize entries in both redo log files and archive log files to complete a recovery.

Accepted Answer

Restoration can use both redo log files and archive log files to recover a database to a previous state, making it possible to recover transactions from the point of failure or corruption. Redo log files contain information about the modifications made to database blocks, while archive log files contain a record of all transactions committed to the database. By combining the information in these two types of files, it is possible to restore a database to a consistent state before the failure or corruption occurred.

Question 13

If a datafile is restored from a backup,then the controlfile will be behind of the datafile in time.

Accepted Answer

When a datafile is restored from a backup, it is typically behind the current state of the database, and the controlfile, which tracks the structure and state of the database, will be ahead of the restored datafile in time.

Question 14

The export utility is capable of recovering individual objects using log entries.

Accepted Answer

The export utility is designed for extracting or exporting data and objects from a database, not for recovering individual objects using log entries. Recovery operations typically involve backup and log files, not export utilities.

Question 15

User and application errors are usually object-centric,such as the dropping of a table.

Accepted Answer

User and application errors can be object-centric, such as accidentally dropping a table or overwriting data in a specific column, rather than being related to the system as a whole.

Question 16

In Oracle Database,restarting the database will always recover from a SHUTDOWN ABORT or a power failure.

Accepted Answer

Restarting the database will not always recover from a SHUTDOWN ABORT or a power failure. In the case of a SHUTDOWN ABORT, the database may be left in an inconsistent state and will need to be recovered using the RECOVER command. In the case of a power failure, the database may be left in a consistent state, but the redo logs may be lost, which will require the database to be recovered using the RECOVER command with the RESETLOGS option.

Question 17

If records are not available in archive log files,they are likely to be stored in undo logs.

Accepted Answer

Archive log files and undo logs serve different purposes. Archive logs are used for data recovery and backup, allowing the database to be restored to a specific point in time. Undo logs are used to maintain data integrity by recording changes made to the database so that transactions can be rolled back if necessary. They do not serve as a fallback for storing records not found in archive logs.

Question 18

A cold backup takes a snapshot of a database,or preferably a part of a database,one file or type of file at a time.

Accepted Answer

A cold backup involves shutting down the database and copying all its files, not just a part or one file at a time.

Question 19

A hot backup is not necessarily a consistent backup across all the files in the backup (if the entire database is backed up in this manner).

Accepted Answer

A hot backup is taken while the database is running and allows users to access it while the backup is being created. This means that the backup may not be consistent across all files since changes may have been made during the backup process. In contrast, a cold backup is taken while the database is not running and ensures a consistent backup across all files.

Question 20

All of datafiles,archive logs,and redo logs can be recovered from a backup,but preferably not all.

Accepted Answer

While all of the datafiles, archive logs, and redo logs can technically be recovered from a backup, it is not preferable or necessary to recover all of them in every situation. For example, if only one datafile or one redo log is corrupted, it may be sufficient to recover only that specific file rather than the entire set. Additionally, restoring and recovering large volumes of data can be time-consuming and resource-intensive, so it may be more practical to prioritize critical files or logs for recovery.

Quiz 15: Backup and Recovery