Modern Database Management: Chapter 11 Review Question 20

Question

Briefly describe four DBMS facilities that are required for database backup and recovery.

Answer

When data is unavailable, damaged, or lost due to application failure, electrical disaster, or human error, the database administrator must ensure that the necessary data recovery is performed. Some data backup and recovery procedures are used to protect loss by taking backup of necessary data. The database management system provides four basic data recovery facilities. They are:

• Backup facilities
• Journalizing facilities
• Checkpoint facilities
• Recovery manager

Their details are as follows:

1. Backup Facilities

The database management system should provide periodic backup of data. Backup facilities produce a copy of data periodically, at least once per day. The backup consists of an entire database, control files, journals, and database objects, including data repository, database indexes, and source libraries.

2. Journalizing Facilities

The database management system should provide an audit trail of transactions, which means that who has accessed the system in a given time and information they accessed are recorded. And, journalizing facilities in the database management system must produce the database changes along with the audit trail.

During the cause of damage, the complete database can be recovered using the audit trail information and the latest database backup.

3. Checkpoint Facilities

This facility in DBMS will not accept any new transactions until all the journal files and the ongoing transactions are completed. This allows all the transaction files and journals to synchronize with the database to create a recovery point.

4. Recovery Manager

This facility will allow the database to restore in its correct condition when the database is damaged and restart the transaction process.