Incremental Vs Differential backup

February 18, 2021,

What is the difference between incremental, differential, and full backups?

Nowadays, data is one of the most valuable assets possessed by any business. Any incident related to significant data loss for a cloud storage backup can have devastating consequences. 

Selecting the correct cloud storage backup strategy makes all the difference when you need to restore that data. Backup strategies can look good on paper, but unless they work for your business, they may be more trouble than they are worth.  It is more important to test your data restores than your backups.

In this guide, we will compare differential backups against incremental backups, and full backups, and explain which is the best backup strategy for your data. These types of backups are the same whether you are using cloud backups or legacy tape-based backups.

Differential backups

Differential backups are similar to incremental backups in that they backup all data which has changed since the last backup ran. A differential backup will contain all the new and modified data since the last full backup ran. 

Even if the last full backup was 5 years ago, the differential backup will backup all data which has been added or modified since then and is present when the backup runs. 

Explanation

Example:

You create a full backup that runs on Monday each week and a differential backup that runs every other day for the rest of the week.

Tuesday’s backup will contain the data that has been added or modified since Monday.

Wednesday’s backup will also contain the data that has been added or modified since Monday.

Thursday’s backup will contain the data that been added or modified since Monday, and so on.

If you need to restore all your data following a disaster you will just need to restore the last full and differential backups. 

You also have the option of restoring data from any of the other differential backups. This is useful if you want to restore data which was backed up on a specific day and is not in the most recent differential backup.

If no data is added or modified between backup schedules, an incremental backup size will be zero, however, the differential backup set will contain all modified data since the last full backup ran.

Pros:
• A full disaster recovery restore using data from a differential backup is quicker than an incremental backup because only 2 data sets need to be restored.

• The primary objective of a differential backup is faster recovery times and fewer backups to manage.

Cons:
• A differential cloud storage backup takes longer to run than an incremental backup, and requires more storage space because a differential backup is larger than an incremental backup. 

Differential backups inevitably grow as you make more changes. Therefore, you should run full backups to reduce the size of the differential backups.

If you have enough time, storage and internet bandwidth, differential backups when used on a cloud storage backup are a perfect choice for recovering your data.

Incremental Backup

An incremental backup will backup added or modified data since the last backup ran. It does not matter if the previous backup was full, differential, or incremental.

Explanation

Example:
You run a full backup on a Monday and an incremental backup on Tuesday. The system will only backup the data that changed since the backup ran on Monday. 

Wednesday’s backup will only backup data added or modified since Tuesday’s backup.

Pros:
• One of the primary advantages of an incremental backup is that it requires less storage space and runs quicker than full or differential backups.

Cons:
• An incremental backup method means every data set must be restored in sequence. This will increase the restore time.

Full Backup:

A full backup is one of the most common data backup strategies. As its name implies, it is a full backup of all your data. Full backups can only run daily if there is sufficient internet upload bandwidth and storage space.

Pros:
• The main advantage of a full backup is that it provides 100% protection of your data every time it runs.
• It is faster and simpler to restore from.
• It offers the best protection for your data.

Cons:
• One of the primary disadvantages of a full backup is that it requires a lot of storage.
• Secondly, it is very time-consuming if you have a lot of data to backup.

Comparison of differential backup to incremental and full backups:

Full backup

Simplest to implement and provides the fastest restore time. Requires the most internet bandwidth and storage space.

Differential backup
Quick restores but uses more storage space than an incremental backup.

Incremental backup
Requires the least storage space and internet bandwidth. Is by far the slowest to restore an entire dataset from.

Conclusion

Any of the three can work in your environment. Contact us if you want some advice on any.

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