Incremental vs. differential backup — What’s the difference?

Incremental and differential backups are reliable backup strategies that help protect your business. They enable your organization to make regular copies of data so you can preserve essential operational information when IT systems unexpectedly go down. Whether your business encounters power outages from weather events or a cyberattack, you can rely on these backup methods to help prepare your organization for disasters and protect your data.

Incremental and differential backups save time and storage space while ensuring your data is secure between full backups. Each offers different benefits and drawbacks depending on your organization’s needs.

What is incremental backup?

An incremental backup copies changes to data since the last full or incremental backup. If you do a full backup on Monday and an incremental backup on Tuesday, the incremental backup would copy modifications made since Monday’s full backup. An incremental backup on Wednesday would copy modifications made since Tuesday’s incremental backup.

Incremental backups are ideal for the cloud since they consume fewer resources. They are small, so they help save time and storage space. When combined with full backups, incremental backups are a cost-efficient option.

If you need to restore data, you will need the media that contains the first full backup and every subsequent backup. If a crash happened on Thursday, you would need to restore Monday’s full backup, then Tuesday’s and Wednesday’s incremental backups. This data recovery process can be time-consuming and complex. If any backup media is missing or damaged, recovery will be incomplete. 

There are a couple of variations of incremental backups, including:

• Synthetic backups: This backup strategy compares modified data from incremental backups with the original full backup. The backup server then consolidates the changes with the full backup to create a synthetic backup. You can save on network bandwidth and reduce restore time.
• Forever incremental backup: With this strategy, you will perform an initial full backup and then take a sequence of incremental backups indefinitely. The backup server stores all backup sets on a large disk array or tape library to automate the restoration process. Forever incremental backups typically take up less space and offer faster restoration than synthetic backups.

What is differential backup?

Differential backups copy data changes since the most recent full backup, regardless of any smaller backups in between. If you perform a full backup on Monday, a differential backup on Tuesday will copy changes made since Monday’s full backup. A differential backup on Wednesday would also copy changes since Monday, so it would include the modifications made on both Monday and Tuesday.

With differential backups, you will only need the first backup and the last differential backup to restore data. Restoration is fast and simple, enabling your organization to minimize downtime after an incident. A differential backup uses less storage space than a full backup, so you can use storage space more efficiently.

The backup file size for a differential backup increases progressively until the next full backup. While it does take less space than a full backup, a differential backup will continue to grow and consume more space as time goes on. 

Incremental and differential backup similarities

Incremental and differential backups have the same purpose — to optimize backup times and save space. A full backup offers the best protection, but it is not ideal for daily use due to extensive time and storage space requirements. Incremental and differential backups save time and storage space when a full backup is not feasible.

Both backup strategies only back up data that has changed since an initial full backup rather than copying the entire dataset every time. This method significantly reduces backup file sizes and the time it takes to back up data.

Differences between incremental vs. differential backups

The most significant difference between incremental and differential backups is how they save time and space. These two strategies enable your organization to protect data, but the resources they require differ. The right option for your organization will depend on your backup requirements, budget, available resources, and data recovery policy.

Backup speed

Incremental backups consistently deal with small files, so they tend to be quicker and more efficient. If your organization produces and modifies large amounts of data, incremental backups could save you time and money. Incremental backups are also ideal when you need quick backups. Differential backups require more time since the backup file size increases daily.

Data restoration speed

Differential backups offer faster restoration speeds than incremental backups. They only require the first full backup and the latest differential backup to restore all of your data, making them the ideal choice in disaster recovery situations where downtime is unacceptable. Rapid restores are critical for various industries with time-sensitive projects or mission-critical systems.

While differential backups only require two backup sets, incremental backups could require a much larger number of backup sets. You will need the first full backup and all subsequent incremental backups to restore data. The restoration process gets more complex and time-consuming the longer it is since the last full backup. Restoration can also become more difficult if backup media is shipped off-site since you will need to retrieve the media before beginning restoration.

Storage space

Since incremental backups are usually small, they require less storage space. Differential backups will take more storage space the longer it has been since the most recent full backup. Small businesses with limited storage space can benefit from incremental backups, while enterprises with sufficient storage space for large backup files can accommodate either incremental or differential backups.

Business resources and requirements

Incremental backups save on storage space and network bandwidth, making them a cost-effective option when paired with full backups. Reduced data transmission with smaller data files can lower the impact on network resources. 

Differential backups get costlier over time since they require an increasing amount of storage space, so they may pull on more business resources. Some organizations need to maintain strict regulatory compliance, so a comprehensive backup history provided by differential backups may be necessary.

Protect your data with Zmanda

Using the right backup strategy for your organization is crucial to minimizing downtime, increasing cost savings, and protecting your data. Incremental and differential backups offer various benefits depending on your organization’s needs and budget. 

Zmanda has been a trusted backup solution provider since 1991, helping enterprises find cost-effective backup options that promote business continuity. We provide versatile backup strategies, including full, incremental, and differential backups. You can choose the approach that best suits your specific needs and recovery point objectives (RPOs).

Request a free trial today to see how our automated backup solutions can save your organization time and resources.