Incremental backup

Incremental backup definition

An incremental backup stores only data and files that have been modified since the previous backup was conducted. The sole purpose of incremental file backup is to capture any changes that have happened since the last archive.

In IT, and specifically in data recovery and backup, it’s usually less important whether the previous backup was another incremental backup or a full backup. The consequences may be important, however.

What is incremental backup?

An incremental backup is among a few basic techniques for securely archiving data and files. Users often compare the full backup to the incremental backup to contrast the typical method as an alternative.

An incremental backup process always relies on a prior initial full backup. If an incremental backup is taken before a full backup is performed, the backup system will force a full backup instead. A full backup will cover all folders and files throughout a system. No new information should be lost if full and incremental backup methods are combined over time. A complete restore from such a system would require restoring the full backup, followed by restoring the data found in each incremental backup.

A related concept is a differential backup, which typically backs up any data that has changed since the last full backup. Differential backups may be combined with incremental backups. For example, a company might perform a monthly full backup, followed by weekly differential backups and daily incremental backups. A complete restore from such a system would require restoring the latest full backup, the latest differential backup, followed by any incremental backup since the latest differential backup.

What are the common types of backups?

Full backups, differential backups, and incremental backups are all fairly typical backup methods. Less common types such as forever-incremental backups and synthetic backups. Here is how the common types of backups compare.

Full backups represent complete copies of all configured data. It’s essential to have all data entirely backed up, but this backup is best used periodically. Creating a full backup consumes far more resources — including time, storage, and network bandwidth — to implement frequently.

Incremental backups save time and resources because they reflect only what has changed in the data since the last backup — whatever type of backup it was. This option consumes less storage space and time, but it also means a more difficult restore process. This is because it essentially means restoring both the last full backup as well as the last incremental backup.

A differential backup, sometimes called cumulative incremental backup, also focuses solely on changed data. However, the differential backup restores back to the last full backup, where the incremental backup just goes back to the last backup of any type.

Comparing incremental vs differential vs full backups, then, the incremental backup sticks to only the most recent changes from the last backup of any kind. The differential goes back to the last full backup, and of course, the full backup is just like it sounds.

How full backups are performed, or if they are performed at all, can vary greatly between backup systems. An incremental-forever approach only performs one full backup, followed by incremental backups forever. A subset of this type is a block-level incremental-forever backup, which stores on the blocks that have changed since the last backup, versus a typical incremental backup that stores all files that have been created or modified since the last backup.

Full backups can also be created via a mechanism referred to as synthetic full backups, where a full backup is constructed by copying data from backups that have already been created. A synthetic full backup consumes no resources of the system being backed up; only the backup server and its storage are used.

See the discussion below for more advantages and disadvantages of full vs incremental vs differential backups.

Types of incremental backup

Traditional incremental backups and incremental forever backup/forever incremental backup are all possible types of incremental backups. They are usually combined with an occasional traditional full backup or a synthetic full backup.

Just like a standard incremental backup, a forever-incremental backup begins with a full backup; however, from that point forward, the system only conducts incremental backups—no periodic full backups at all. After enough time, full restoration is possible with reorganized stored data from all backups.

Advantages of the incremental forever backup strategy include fast incremental backup and quicker ability to restore operations during critical times. They also include low requirements for storage space and reduced demands on the network.

A traditional full backup backs up all data from the original system being backed up. A synthetic full backup does not use the original system to create a new full backup.

Instead of performing another full backup from the original system, the system consolidates its incremental backups to synthesize a new “full backup.” This then becomes the new starting point, and incremental backups continue from that point.

Advantages of the synthetic full backup include faster backups and a reduced load on the backed-up system (i.e. the backup client). They also reduce demands on the network.

Explain incremental vs differential backup

The primary difference between incremental and differential backup focuses on the source file for backups and when it is consulted.

Both the incremental backup and differential backup are efficient versioning systems, focusing on only the data that has changed to save disk space and time. The main distinction is simply which backup they use as a reference point and how far back they go.

Even in the industry, these types of backups are often called different things. For example, a differential backup may be referred to as a cumulative incremental backup, whereas an incremental backup might be called a differential incremental backup.

The difference between differential incremental and cumulative incremental backups is less a matter of confusing technical details and more a matter of semantics. It is also the same difference in the source file for the backup reference.

For now, consider the difference between incremental and differential backup with examples. Both of these techniques save disk space and time by backing up only files and data that have changed. This makes sense, since most data on any given computer changes infrequently, if at all.

For example, your team conducts a full backup on Monday. Now you can either conduct differential backups moving forward or incremental backups — or some combined strategy.

If you conduct differential backups, each one will back up everything that has changed since Monday, every single time. So Tuesday’s backup has everything new since Monday, and so does Wednesday’s — even if some of the data didn’t change from Tuesday to Wednesday.

If you conduct incremental backup instead, you will capture only what changed, every time. The result will be smaller capsules of only altered data. It takes less time and burns less storage space, but it can take longer to conduct a complete restore – depending on your backup system. This is why many people use both differential and incremental backups.

How to conduct incremental and differential backups?

Many businesses perform a daily incremental backup as part of their strategy. This allows them to capture changed data without incurring excessive costs.

How to create incremental backups will depend in part on your business’ size and the nature of your data. How to do incremental backup changes slightly, because best practices shift depending on your business and data goals.

For both incremental and differential backups, modern backup and archiving solutions have workflows to take users through the execution process from initial implementation through the final validation of the data archives.

Is incremental or differential backup better?

What is the difference between differential backup and incremental backup? Primarily speed and cost, for both storage and restoration time.

The first incremental backup and differential backup difference is about backup speed. This has to do with how incremental backup works.

Since incremental backups are focused on the smallest amount of data, they are the fastest to perform. In fact, they can often be performed hour by hour or even minute by minute.

Differential backups are faster than full backups, but the longer it has been since the full backup, the longer they take to conduct. On the other hand, incrementally updated backups provide a speed disadvantage in the restoration process.

In terms of how to restore incremental backup files, the restore operation can be slower than that for other backups. Full backups are basically ready, and differential backups take less reconstruction, typically, to arrive at a full dataset.

In fact, in certain situations, the backup software may need all iterations of the incremental backup to restore the data. It also won’t be able to restore it should any of the pieces be missing. In such systems, performing an occasional differential backup will help speed up recovery.

Incremental backup advantages and disadvantages

Obviously, a full backup has its advantages: it covers your data completely and you don’t risk losing it. However, full backups take a long time and lots of storage space. In addition, each complete copy of data carries the risk of a breach with it.

The advantages of incremental backup basically address these flaws. These incremental backup advantages include far less storage space requirements, lower costs, and faster backup times. By contrast, the disadvantage of incremental backup comes in the complexity and time of restoration.

Some modern backup systems, especially cloud-based backup, do not need to perform occasional full backups in order to speed restore times. They store backup data in object format, and restore all data and files simultaneously, regardless of how it was backed up.

What is reverse incremental backup?

The reverse incremental backup or backup reverse incremental process, like other incremental backups, begins with a full backup. It also shares some qualities with the synthetic full backup.

After the full backup, in the reverse incremental backup process, the system performs incremental backups. Each time, it then reversibly “injects” the latest incremental backup into the full backup.

The result is a synthesized full backup that includes all of the latest data. This updated full backup allows for faster restoration, relieving some of the issues presented by traditional incremental backups.

How does incremental backup software work?

Incremental backup software basically works by including the functionality to conduct incremental backups in one place. Incremental file backup software can protect your business’s critical data from anything from viruses, errors, and corruption, just like conducting a full backup.

However, it does this as an all-in-one solution. This way you do not have to manage the schedule or strategy manually.

What is the best incremental backup software?

The best incremental backup strategy will be specific to your business. However, in general, the best incremental backup software should be able to handle several tasks.

Strong incremental backup software should use less space by compressing and deduplicating file contents. It should encrypt and protect your data and offer cloud protection with high levels of uptime on dedicated servers. It should allow you to choose different types of backups and customize your backup strategies based on your requirements and goals.

The best incremental backup software offerings also allow users to restore systems simply and offer support, fixes, and updates. They work on schedule, seamlessly, without intervention from the user, until they are needed in times of crisis.

However, all software has limitations, and there are other incremental backup tools available. A cloud solution, for example, eases disaster recovery when infrastructure is damaged.

Experts recommend a plan that implements more than one of these backup approaches, including a periodic full backup, as part of an overall data-integrity strategy. You should also conduct a full backup anytime you make a major alteration to the system, such as installing new software or updating your operating system.

Does Druva offer a solution?

Druva’s flexible enterprise cloud backup system includes an incremental backup tool — and much more. Its public cloud-native architecture allows for secure, simple, scalable enterprise cloud backup and restoration, even where bandwidth is scarce.

No hardware or software means there is no hassle in deployment. In fact, cloud incremental backup delivers a 50 percent lower TCO. Schedule your backups once and don’t think about them again until it’s time for a change.

Learn how Druva eliminates the cost and complexity of managing a global backup infrastructure.

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