Hot and Cold backups - Oracle

 

Cold Backups:

Cold backup or offline backup is done when there is no user activity going on the system. It is taken when database is not running or no users are logged in. No changes in database are allowed during cold backup process. Cold backups can be used for application which does not interact with the users directly for example : any student record maintenance database can be backed up through cold backup as only users of the database would be university staff and the backup and recovery process can be well planned and communicated to the staff members.

Advantages:

• Cold backups are generally easy to administer.

• There is slight performance gain when doing cold backups as compare to hot backups as the database does not have to copy archive logs to the disk.

• It requires low maintenance and is generally more secure.

   

  Disadvantages:

• Cold backups do not provide point in time recoveries, which is the biggest disadvantage of the cold backups.

• Database must be turned off while the backup recovery process is in progress.

• It requires enough disk space.

• It does not provide an option to back up a single table.

Hot Backups:

On the other hand hot backups are taken when the database needs to run all the time. This backup allows the changes in the database when backup is being taken. It is also called online backup. Hot backups are used for the applications, which needs to be up and running 24*7*365 i.e should always be available for the end user. Any down time can lead to either serious dissatisfaction among users or a loss in revenue stream. For example : any product data on amazon website can not be backed up in cold backup as it would lead to loss in revenue stream as well as dissatisfaction among customers.

 

 

Advantages:

• The database is always available for use and database can be backup and recovered at any point.

• Point in time recoveries can be used.

• It provides table space or data file level bakcups.

   

Disadvantages:

• Generally, hot backups are difficult to maintain.

• If the backup fails then point in time recoveries cannot be used.

• Hard to recover if the backup files are faulty and backup was not validated.