Database Backups - Hot Backup vs. Cold Backup
<font color=#0000CC>Data and information are as important for an organization as blood in human body. In case data and information become unavailable due to any reason, all the working of the organization stops and it becomes unmanageable loss. In order to avoid such big loss, Database Administrator (DBA) must take backup of his database frequently according to the nature of the database. Normally full backup are done after one week but incremental backup are done on daily basis. Backup can be defined as second copy of original database produced by backup facilities provided by DBMS or operating system. This second copy or saved copy of original database is produced on separate storage media such as magnetic tape, external hard disk and on CD-drives. These should be placed in a separate and secure location, where unauthorized persons do not have any access. The best way, you can store your database backup online using Internet and you can access this backup any time, from any location using Internet. There are two important types of backup.
You can say hot backup is dynamic or active backup. Hot backup is taken when database is running and data is being updated, added, or read by its users but doesn't handle running transactions. Only database management system (DBMS) facility can be used to take hot backups. Make sure that hot backups should only be done during low working hours. Hot backup is taken in environments where database needs to remain online 24-hours a days and 7-days a week, because they do not require downtime as in cold backup.
Cold backup is taken when database is offline, not accessible for updating and users cannot do anything on the database.. DBMS as well as operating system facilities can be used to take the cold backup. Normally, cold backup is taken at the end of a working day or at weekends when database comes offline. Cold backup is suitable in environments where database is not running 24-hours a day. Instead, there are sometime intervals when it remains off.
Backups can be taken manually through the DBA or these can be taken automatically by configuring the DBMS. In case of automatic backups, you must specify day, time, and location on storage media where DBMS will take the backups. These settings are required when configuring the DBMS.</font>