What is Backup and recovery in data warehouses?

Backup and recovery define the process of backing up records in the method of a loss and setting up systems that enable that data recovery because of data loss. Backing up data needed copying and archiving computer information, so that it is applicable in case of data deletion or corruption.

The goal of the backup is to make a copy of data that can be renewed in the event of a primary data failure. Primary data failures can be the outcome of hardware or software failure, data corruption, or a human-caused event, including a malicious attack (virus or malware), or accidental removal of information. Backup copies enable data to be resaved from a previous point in time to support the business recovery from an unintended event.

It can be saving the copy of the data on the independent medium is demanding to secure against primary data loss or corruption. This new medium can be as simple as an external drive or USB stick, or something more meaningful, including a disk storage system, cloud storage container, or tape drive. The backup medium can be in the same area as the primary data or a remote area. The feasibility of weather-related events can validate having copies of data in remote areas.

There are various types of backup which are as follows −

  • Complete backup − The entire database is backed up simultaneously. This includes all data files, control files, and journal files.

  • Cold backup − It is a backup that is taken while the database is completely shut-down.

  • Hot backup − It is a backup that is not cold and is considered to be hot. The term hot is used because the database engine is up and running. A backup of the database is made when it is open and potentially in use. The DBMS will need to have special facilities to ensure that data in the backup is consistent.

Recovery is the phase of reconstructing a database after some element of a database has been hidden. The recovery model of a current database is inherited from the model database when the new database is generated. The model for a database can be changed after the database has been created.

  • Full recovery model − It provides the most flexibility for recovering the database to an earlier point of time.

  • Bulk-logged recovery model − Bulk-logged recovery provides higher performance and lowers log space consumption for certain large-scale operations.

  • Simple recovery model − Simple recovery provides the highest performance and lower log space consumption but with significant exposure to data loss in the event of a system failure. The amount of exposure to data loss varies with the model chosen. Each recovery model addresses a different need.