Database Backups: Logical vs. Physical, Hot vs. Cold

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Because databases support business critical application, it’s important that you implement a solid data protection and disaster recovery process from the very beginning. Strong fundamentals are important at this early stage, because it will be harder to modify your backup process further down the road.

You need to implement an air-tight backup plan — based on strong fundamentals — early on, and stick to it for the long term.

When it comes to database backups, you first need to determine whether you will be employing “Cold” or “Hot” backups, and whether you need to recover “Physical” or “Logical” data elements as part of data protection plan

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Cold vs. Hot Database Backup

 
A Cold backup process requires the database to be locked up or shut down during backup.  This is the simplest and most common method used to back up databases.

A Hot database backup can be performed at any time because they do not require that the database server be taken off-line for maintenance. (Although some Hot methodologies do place temporary locks on certain parts of the database) Hot backups are better suited for companies who do business on a twenty-four hour basis, or have little tolerance for downtime.

Your choice of Hot or Cold backups should be covered as part of your Recovery Time Objectives. (RPOs)

Logical vs. Physical Database Backups

 
Once you’ve made a decision about your uptime requirements, you need to make decisions about what kind of data you will be backing up from your databases.

  1. Physical Files, such as text files, are stored as a single document on your hard drive. Although databases consist of many complex elements, these are usually aggregated into simple files on your server’s hard drive. These files can easily be backed up just like any other files on your system.
  2. Logical Data Elements such as tables, records and their associated meta data are stored across many different locations. Backups for tables and other logical database elements usually require special tools that are designed to work with your specific database platforms. Although these types of backups are more complex, they offer more granular recovery capabilities. This is especially true when doing point-in-time recovery of tables that involve complex transactions and inter-dependencies.

 

Logical database backups are critical for granular recovery of specific components. And Physical backups are useful for full disaster recovery scenarios.

The choice between Logical and Physical database backups should be covered as part of your Recovery Point Objectives. (RPOs)

Without the proper support and guidance, database backups can be complex and time-consuming. And because of all the complexities involved, it’s usually better and safer to rely on the help of experienced database backup professionals. For more information on the logical versus physical backup, see this short video.

https://youtu.be/quXHYCQONdY