Full, incremental and differential backups: what’s the difference and which should you use for OT in 2026?

 

Attempts to explain the differences between full, incremental and differential backups all too often stop at definitions. Knowing how each method works is valuable, but it’s far less important than understanding why the differences matter.

Your choice of backup type has a direct influence on downtime cost, storage planning, and in the competitive environments of 2025 making the wrong choice can be disastrous.

This is especially true in OT and industrial environments. A machine that must return in an identical state or a system that cannot be taken offline for long will not respond the same way to every backup method. And while some organisations believe full backups are always the most reliable approach, the practical benefits of incremental and differential backups are significant.

Incremental and differential backups take significantly less time than full backups, reducing the impact on critical systems - essential when you cannot afford to have a SCADA system dedicating resources to backup processes all day. They also consume less storage and generate far less network traffic, which becomes critical on older OT networks with limited bandwidth where repeatedly taking full backups simply wouldn't be practical. Understanding where that caution comes from and how to evaluate it properly is key.

Choosing a backup type is a strategic decision based on the behaviour and operational needs of the individual system. So let’s take a look at up to date definitions of each model, what they mean for your RPOincremental and differential backups in the right context.

Most importantly, how should you select the right approach for the systems that matter in your environment.

 

A full backup contains everything: the entire disk image (or all selected files) at the moment it was taken. It is simple, self-contained and quick to restore because it has no dependencies. The drawback is the load on the system and the time required. Full backups take the longest to create and can be difficult for machines that cannot be interrupted or slowed down.

A differential backup captures all changes made since the last full backup. Restoring one requires only two files: the full and the chosen differential. Differentials start small but grow in size and duration the longer you go without a new full. They offer a solid balance between simplicity and speed when supported by regular full backups.

An incremental backup contains only the changes made since the last backup of any type. They are the fastest to create, place the least load on systems and keep backup windows short. Restoring requires the full chain: the full backup, any differential and all incrementals up to the chosen point of recovery.

These explanations are useful, but only when considered alongside how your systems behave in practice: how often they change, how quickly they must return after an outage and how much downtime they can tolerate for backup.

 

Backup type matters more in 2026 because estates are changing faster, outages are costlier and regulators expect tighter evidence of recoverability. Each backup method affects how frequently you can protect a system, how much storage you consume and how quickly you can recover.

These factors shape your RPO and RTO. A machine that changes often needs frequent backups. Systems with strict uptime requirements must minimise backup-window impact. And in environments where the machine must return exactly as it was, imaging becomes essential.

 

Full backups offer a fast restore path but may take too long to run frequently enough to support a strong RPO. Differentials provide a balance: straightforward to restore, without the overhead of a full backup each time, as long as fulls are scheduled routinely.

Incremental backups minimise both RPO and backup window impact. They are quick to capture and easy to schedule. Although restores involve more files, the ability to run incrementals frequently usually more than compensates.

 

Despite these practical advantages, some suspicion still surrounds incrementals. Because Macrium talks every day with organisations improving their backup strategies, we understand that teams worry if one file in the chain fails, everything that follows might be unusable. It is an understandable fear, especially for systems that are old, sensitive or difficult to replace.

But the mathematics of storage actually work in favour of incrementals. Consider this: two 500GB full images use 1TB of sectors to provide just two restore points. One 500GB full image followed by ten 5GB incremental images uses only 550GB of sectors while providing eleven restore points. Fewer sectors in use means a smaller surface area for potential corruption - incrementals actually reduce the risk at a fundamental level.

In practice, the real risk lies less with the incremental method and more with how the wider strategy is designed. Short chains, regular full backups, sensible scheduling and consistent validation make incrementals one of the most reliable and efficient methods available. They reduce the time required to protect a system and support frequent recovery points. When used as part of a planned, well-maintained schedule, incrementals can form the backbone of a resilient, modern backup strategy.

This is where approaches like the 3-2-1-1-0 strategy become valuable. Multiple copies of backups across different locations, combined with regular verification to ensure restorability and detect data errors, mitigate corruption risk regardless of backup method. In most environments there is no need to shy away from incremental backups. The important thing is simply to avoid poorly designed chains and ensure your validation processes are robust.

 

In many OT and industrial settings, the available backup window often determines which backup type is workable. A production line cannot pause for a lengthy full backup, and critical systems in energy or healthcare cannot risk performance dips during imaging. Incremental or differential backups allow protection to remain frequent without disrupting operations.

Storage capacity matters too. Full backups require the most space, differentials grow the longer they run, while incrementals stay compact. A mixed approach, often structured through a Grandfather-Father-Son schedule, keeps storage predictable while still providing the recovery options you need.

 

All three backup types can be used with image-based backups, but in OT environments imaging itself is central to resilience. Files alone are not enough. The entire state of the machine needs protecting, because these systems often rely on older Windows builds, proprietary drivers, calibration files and hardware behaviours that standard installations cannot reproduce.

Imaging captures all of this and dramatically improves RTO. The machine can return exactly as it was, with every dependency intact - far faster than manually rebuilding systems, restoring files individually, or troubleshooting failures piece by piece. In time-sensitive OT environments where downtime carries significant cost, this speed advantage is critical.

 

Regardless of which backup type you choose, the backup set is only as strong as your ability to restore it. This is why validation remains essential. It confirm that the chain is intact, the image will boot and the environment behaves as expected. And as we regularly remind teams discussing backup with Macrium, the backup type does not alter the rule that “if it has not been tested, it cannot be trusted”.

 

There is no universal best option. The right approach for you depends on how often your system changes, how quickly it must return after an outage, how much downtime it can tolerate for backup, the storage available, how the machine behaves in production and what your compliance regime requires.

In many environments, incremental backups supported by periodic fulls and a well-planned schedule provide the strongest balance of speed, resilience and efficiency. Differential backups offer a middle ground, while full backups remain essential for resetting retention cycles and providing a straightforward, self-contained restore point.

“Think it through carefully,” advises Macrium’s CPO, Craig Mackay. “How you choose to back up governs how confidently you can recover.”

 

If you’d like to review your current strategy or explore how these backup types apply to your own systems, we’re here to help.