Difference Between Differential and Incremental Backup Strategies

These days, the possibility of a cyber attack affecting your files – whether they are on a remote network or a local workstation – is no longer a matter of IF, but WHEN. You can keep your OS and softwares perfectly up to date and install the best anti-malware available, but you’re still not safe from hardware crashes and physical media corruption. If you really value your data, you need to have a regularly updated backup of your sensitive and mission-critical data.

However, regular backups can be time consuming especially if you have gigabytes of data to back up, which is especially made worse by the fact that large organizations will have accumulated terabytes of data throughout the years. With conventional methods of backing up files, the backup you have created will already be obsolete by the time you have finished, as new sets of data has probably already appeared. In order to solve this conundrum, there are so-called “smart” backups that save both time and disk space by only backing up modified and new files. There are currently two types of smart backups – Differential and Incremental.

The fundamental difference between differential and incremental backup strategies lie not in their overall efficiencies, as they are both viable strategies, but in their respective strengths and weaknesses. Choosing one over the other will depend on your needs and requirements as an organization, as well as your capabilities. But first, let us define the two backup strategies.

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Differential Backup

Differential backup is a form of backup that will only copy data that has been modified or created since the last full backup. That means if you made a full backup on Monday, then Tuesday’s differential backup will contain a copy of all the files that have changed since Monday, and Wednesday’s differential backup will contain a copy of all of the files that were changed since Tuesday and Monday and so on, until you make another full backup, in which case it will use that backup as a starting point for succeeding differential backups.

Incremental Backup

As the name implies, an Incremental Backup only does back ups in increments, in the sense that it only makes copies of all the files that were modified or created since the last backup, regardless of whether that last backup was a full backup or just an incremental copy.

Comparison of Differential and Incremental Backup Strategies

The main advantage of a differential backup strategy is that a complete restore is fairly speedy, as the process only requires you to restore the last full backup and the latest differential backup regardless of how long ago the last full backup was. A complete restore using an incremental backup, on the other hand, requires you to restore all of the backed up copies since the first ever full backup, which can be tedious and time consuming if you’ve already backed up a lot of files.

However, Incremental backup also has a specific strength that makes it better than differential backup under certain cases. For instance, fewer files are copied in the period between full backups, so it doesn’t require as much time disk space, whereas differential backups have to handle more data as more differential backups are made, requiring you to do a full backups regularly in order to save disk space and time.

Conclusion: Which One Suits You?

As stated above, there’s really no such thing as an overall better strategy between differential and incremental backup strategies. They both have specific strengths and weaknesses that will make either one appeal to certain people and/or organizations depending on the needs and capabilities.

If you have a lot of disk space available and want the ability to do complete restores fast (at least, faster than the other method), you should go with a differential backup strategy. But if disk space is limited and you don’t have the time, manpower, or tools needed to make regular full backups, then an incremental backup strategy will suffice. In a way, this means small organizations or home users who just want their data to be safe and secure in the unlikely event that they lose everything should go with incremental, while large organizations that have the budget, need their data to be safe, and have to maintain fast response times in the event of data loss or corruption should go with incremental.

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