What is the difference between data backup and data replication?
Backup and replication are often treated as one and the same. They’re not. There are distinct differences between the two which need to be considered when implementing a disaster recovery strategy.
Data backup involves making offsite copies of data which can be restored if the original is damaged or lost. Backups are usually run once every 24 hours, or weekly at an absolute minimum.
Replication is the process of copying data from one location to another, for example between two data centres. Replication is done instantly to create real time copies of files.
So whereas backups are images from the last time you performed a backup, a replication will give you a complete, up to the minute (or even second) rendering of a file.
Don't confuse your replication with your backup
So having replication in place means that you can forget about backups, right?
Backups and replications serve different purposes, and are best used in tandem.
Valuable for compliance, a backup is usually used to protect against data loss, but doesn’t ensure business continuity.
Replication on the other hand, is designed to reduce or eliminate the risk of downtime through outage, whether planned or unplanned, through automatic failover to the secondary site, should the primary site fail.
Why do I still need a backup?
If disaster strikes (fire, flood, theft for example) and a business experiences an outage, the financial implications come thick and fast. Having replication in place, and the ability to failover to a secondary site - which is a mirror image of your primary site - means business as usual and the ability to drastically reduce Recovery Time and Recovery Point Objectives (RTO, RPO).
However, because everything on the primary site is copied over to the secondary site, this means that mistakes are also replicated. So any errors, corruptions or accidental deletions are also instantly copied across. On this occasion, a data backup would be needed to restore to correct version of the file.
So although replication is an effective business continuity tool providing near-instant recovery, it doesn’t tick the box for historical data copies or to maintain compliance with legislation.
You need to implement both data replication and data backup into your disaster recovery strategy for a robust approach to business continuity.