What is Incremental Backup?


Incremental backup entails a backup method wherein each consecutive backup solely captures the alterations made since the last full backup.This article will look at the pros and cons of using this type of backup compared to other options, and what MSPs and IT professionals should know about relying on incremental backups for their customers and corporate environments.

What’s the state of backup today?

There’s no IT professional on the planet who doesn’t realize how important backing up data is for a business. Anything from human error to a system failure to a cyberattack could cause data loss, and with today’s pace of change, backing up data as often as once a day is not unusual. However, not all organizations are listening to this advice, and the stats show that 14% of data is not backed up at all, while 58% of data recoveries fail. Ouch.

Why don’t businesses create regular full backups?

Of course, a full backup will provide the best protection for your data, and it is also the simplest form of backup, where all data is stored in a single file which makes it faster to restore and easier to track.

However, that’s not the only consideration on the table for today’s decision makers. It’s a lot more expensive and time consuming to do a full backup every single day or week, and the storage space is actually being wasted when much of the data being backed up hasn’t changed from the previous backup. Other considerations include security. With a full backup, all the data is stored in a single place, so if a cyberattack manages to access your data storage – you’re stuck. As a result, many organizations are looking for smarter, more cost-effective and less time-intensive methods of backing up their data.

How do incremental backups solve these challenges?

In contrast to a full backup, incremental backups are much faster and more cost-effective, as with every backup, you are only storing the changes that have been made since the last backup. This approach is usually done alongside periodic full backups, and it relies on a full backup to work. So for example, you might have a full backup every Wednesday, and then Thursday’s incremental backup will only store what has changed between Wednesday and Thursday. Friday’s incremental backup will store what has changed from Thursday to Friday, and so on. If you’re completing a full backup once per week, the following Wednesday, another full backup will be done.

One downside to incremental backups is that it will take longer to restore your data as it is not a single file, and it needs to be put back together from all the single versions of changes from day to day. In addition, if any of the backups fail, you might end up with gaps in your data. Let’s say you only perform a full backup once per month. With incremental backups you will often need to piece together 30 files, and rely on them all being complete and clean.

What’s the difference between differential and incremental backups?

The approach we’ve described above is slightly different from a differential backup, which will always backup everything that has changed since the last full backup. That means that if you have that full backup as usual on a Wednesday, and then rely on differential backups in between, your Thursday backup will backup all changes in the past 24 hours, and your Friday backup will backup all changes from the past 48 hours, and so on.

This has become a popular method of backing up which can give you the best of both worlds. You get a faster restore time than with incremental backups alone, as you only have two backup containers, one with the full backup, and one with the latest differential backup. In contrast, with incremental backups you have another file for every single day since the last full backup. Differential backup is faster than full backups, and yet you have significantly less demand in terms of storage and therefore cost. While you’ll still need more storage than incremental backups, in today’s cloud-enabled world, public cloud storage can be affordable and easy to scale.

Top tip: Make sure to perform a full backup regularly, as differential backups will get larger and larger over time, taking up an increasing amount of storage.

To sum up, here are the pros and cons of each type of backup:

Full backup: Best protection for your data, but takes the most time and storage space, therefore it’s definitely the most expensive choice.

Incremental backup: Smaller sized files means less storage and time, but these also carry the most risk and complexity to utilize when you need the data.

Differential backup: Less time to restore than incremental backups, but may need greater storage/have rising costs over time.

How to establish best practice for testing backups

Whichever approach you use for creating backups, it’s so important to have a process in place for testing your backups. After all, your backups are your failsafe, your “in case of emergency – click here” button, and so you can’t afford to have these go wrong. Especially if you’re using incremental backups, you want to be sure that each file is clean and not corrupted, as you’re only getting one chance to back up this data.

Make sure you are utilizing automation or applications that track successful backups, to show you when backups fail or are incomplete. Atera integrates with Acronis for backup, and will offer specific error messages so that you can see what went wrong in case of a problem, for example, “There is no data available for the backup”, or “No volumes selected for snapshot.” You can then use the support portal to find your error message and troubleshoot any issues to ensure you’re left without any backup gaps.

Don’t forget to set a schedule for testing and checking backups, simulating any number of potential events, such as power outages, ransomware attacks, or simple human error. This way you’ll be two steps ahead with a robust incident response plan if the worst occurs – whatever that might be.

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