Incremental vs differential backup – what is the difference?

Every company needs a backup – this is a fact no one would deny. As the saying goes, there are two types of people in the IT world – those who back up and those who are yet to back up. In the event of the system malfunction, hacker attack, computer virus infection or malicious user activity, or just simply a human error (accidental deletion of data), a backup copy of our data is the only way to be back on track. Backup copies are simply the essential part of the IT infrastructure of an organization.

Simply put, a backup is a full copy of all relevant computer data in the company. However, nowadays the amount of that data is so large that creating backups may take a considerable amount of time. That is why new methods were invented – a differential backup and an incremental backup.

Differential backup

When a company operates on a large amount of data that is constantly growing or changing and does that on a daily basis, a full backup is simply impossible. The process is time-consuming and usually takes a lot of storage space. To address this problem, a differential backup method was invented.

The differential backup takes a copy of all items that were changed since the last full backup.

For example, a full backup was performed on Sunday. Next, on Monday a differential backup job takes a copy of items that were changed or added since Sunday. On Tuesday, the job takes a copy only of the data changed since Sunday, etc.. The cycle is repeated until the next full backup is performed.

Pros:

• The process is much quicker than a full backup since it only takes a copy of what was changed.
• The backup copy itself takes far less storage space than when a full copy is created each day.

Cons:

• The size of the data differences part grows with each cycle. If the cycle is long (e.g. the full backup is performed once a month and the differential is taken every day), at the end of it the size of the archive might be quite big and the process itself pretty lengthy.

Incremental backup

The main difference is that the incremental backup takes a copy of items changed or added since the last incremental backup job. For example, the full backup was performed, as before, on Sunday. On Monday, the incremental job kicks in and takes a snapshot of all data that was changed since Sunday. On Tuesday, the job takes a copy of all changes since Monday, on Wednesday it backs up everything changes since Tuesday and so on.

In other words – the process works in a chain order creating the copy of data modified or added since the last backup job.

Pros:

• The backup process is even faster than the differential job, not to mention the full backup. It is, in fact, so fast that it can be performed every hour or even minute.
• Each iteration of the backup job copies just the data that was changed. Therefore, only a small amount of storage is required each time.

Cons:

• In some cases, the backup software requires all iterations of the incremental backup for data restoration. If one of the pieces is missing – the restore is impossible.
• The restore process might take some time as the software needs to rebuild data from separate incremental pieces and also the last full backup piece too.

Summary

In the age of the Cloud, it seems that the incremental backup is the best choice – it is fast, pulls down a small amount of data and can be performed even in real time. If you add advanced data versioning and sophisticated recovery processes that rebuild lost information much quicker even without all the incremental pieces, you’ll get a robust tool that has you covered all the time.

CodeTwo Backup for Office 365 is an example of such software – not only does it back up entire mailboxes (all types of items) from Microsoft Office 365, but it also gives you all the benefits of the incremental backup with a pinch of what’s best in the differential type of the process. You can also back up SharePoint Online. Learn more…