Before jumping into the discussion about differences between differential and incremental backups, we have to go over their so-called predecessor – the first backup type called “full backup”.

Full backup

Full backup is probably the most well-known backup level, probably because it is the most straightforward of them all. Full backup creates a copy of all of your files at that exact moment, and that is all that it does. This backup type might be suitable for small companies as the only one used, but problems with it typically increase  exponentially as a result of the amount of data that needs to be backed up on a regular basis.

Constant backups of large databases often result in a heavy bandwidth usage, i/o bottlenecks, drastic increase of the time it takes for each backup to be done, and more. There is also the fact that due to all of these problems it is physically difficult to  do a full backup more than, say, once a week without running into various problems – and a week of data lost in case of a disaster could easily cause a company’s downfall.

Because a lot of data does not change at all for long periods of time, every full backup will likely include a lot of duplicate data that has already been backed up. However, by using more sophisticated software that offers free incremental backup tools or differential backup type (or a combination of both), this situation can be somewhat avoided.

Differential backup

The first attempt to solve this problem outlined above with Full level backup resulted in differential backup being developed. Differential backup’s prime purpose is to create a backup of all the data that has been changed since the last full backup happened. This approach can drastically change the amount of data that needs to be copied each time, but there are typically still a significant number of duplicate files generated.

Differential backup takes all of the data that changed since the last full backup. As a result, repeated differential backups are likely to have data duplicates. Despite that problem, using a differential backup along with the Full tends to decrease the overall load on a company’s servers and networks since the amount of backed up data drops to some extent. In addition, users of differential backup tend to have much higher RPOs since you can do differential backups much often than the full ones.

Nevertheless, Differential level, for all its advantages may still not be the optimal level to use, and it is therefore a good idea to consider another level called ‘Incremental’.

Free incremental backup tool

Incremental backup is another way to address the difficulties that come with using full (and differential) backups. In this case, an incremental backup creates a copy of all data that was changed since the last backup happened (regardless of whether it was full backup or another incremental).

Performing multiple incremental backups is a popular way of lessening the amount of data that can potentially be lost if there’s a need to restore an entire system from the  backup.

At the same time, incremental backups are not perfect, either. The obvious advantage is the decrease in the storage space taken and the lack of duplicated data. It is countered by the need for every single one of the incremental backups since the last full one to be present to restore the data to its fullest. This also increases the overall restoration time since all of the smaller backups need to be  connected together and then restored as a complete database.

Comparing each of the backup types with the other ones may have limited merit since there are many cases where these backup levels are used in parallel to provide optimal performance and results for any given company. Of course, since so many organizations treat their data as an extremely valuable – even critical – asset, commercial or free incremental backup software is perhaps more popular than  backup software that focuses more on differential backups.

Bacula Community

One example of a popular open source incremental backup software is Bacula Community. Bacula Community might is often considered the best free incremental backup available, offering an especially large range of features and capabilities, all available for free.

There is also a large community that revolves around Bacula, providing support, advice and learning to address the majority of problems in the shortest amount of time with the knowledge-base that comes from thousands of people already using Bacula Community.

You can learn more about Bacula Community and download its incremental backup software for free from their official website here.

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