Data Backup Types Explained

Having an up to date backup of your data is crucial. But what type of data backup – full, incremental, differential or synthetic – is the best for your needs? Check out our guide to the different forms of data backup.

The most complete form of data backup is unsurprisingly known as a full backup, and involves all the data in the dataset being backed up. The downside of a full backup is the space and amount of time it will take. Despite these downsides, it’s still the best form of data backup, so if you can deal with the extra time it takes, particularly if you don’t have a lot of data, then this is the backup strategy for you. Most businesses only perform full backups periodically because of these downsides.

Incremental backups were developed to counter the time-consuming nature of full backups. In an incremental backup, only data that has changed since the previous backup is performed. This is a much quicker and less storage-heavy way of backing up your data. The downside is that when restoring the data in the event of a data loss incident, you’ll need to reconstruct it using the last available full backup and the intervening incremental backups. This significantly increases restoration time. If you performed a full backup on a Monday, and wanted to restore your data on a Thursday, you would first need to restore Monday’s full backup, followed by Tuesday, Wednesday and Thursday’s incremental backups. Furthermore, if any of the incremental backups are damaged, your backup will be incomplete.

A differential backup is very similar to an incremental backup, in that both start with a full backup, and each subsequent backup only includes the data which has changed since then. The key difference is that a differential backup contains all data since the last full backup, rather than the last incremental backup. For example, if you performed a full backup on a Monday, the backup of all new data the following day on the Tuesday would be both an incremental backup and a differential backup. But the divergence comes on the Wednesday. A differential backup would only backup data written since the previous backup i.e. Tuesday, whereas a differential backup would back up data since the last full backup, i.e. Monday. Differential backups have much shorter restore times, giving them the edge of incremental backups.

A synthetic backup is a variation of an incremental backup that begins by taking a full backup, followed by a series of incremental backups. Synthetic backups takes things further by combining the last full backup and all the intervening incremental backups and producing a full backup. The user ends up with a full backup that is identical to a full backup produced the traditional way. Synthetic backups allow for much shorter restore times, and offer all the benefits of a full backup, but with the reduced backup times of an incremental backup.  

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