Differential Backup Volumes

Differential Backup Illustration

Differential Backup (level 1)

A special type of Cumulative Incremental Backup that copies the files that have been modified or created since a previous Full Backup.

These graphs were generated using backup statistics gathered from a production backup server. The same data has also been graphed with respect to the size of the corresponding Cumulative Incremental and Partial Cumulative Incremental backup volumes to show the increased savings that PCI Backups provide over both Cumulative Incremental and Differential backups volumes. In this two week sample, 2 level PCI Backups were 36% smaller than the corresponding CI Backups and 58% smaller than the corresponding Differential Backup.

You may have noticed that the Differential backup volume is actually smaller than the sum of the daily True incremental Backup volumes added together. This is because a True incremental Backup volume consists of both new and changed data. The Differential is new or changed data since a previous Full Backup. Therefore, the Differential volume will almost always be smaller than the sum of the TI volumes.

NOTE: Alternative Uses of Terminology Explained

Some vendors may refer to the term “cumulative incremental backup” when describing their level 1, Differential Backup, capability. We use the term more generally to describe the behavior of a backup at any incremental level (any level except 0) that accumulates data changes since any previous lower level backup (including level 0). Our ability to generate multiple levels of synthetic backups (not just full or differential) provides our customers with a synthetic backup technology that is far more flexible and advanced.

Some vendors may use the term “differential incremental backup” when describing their True incremental Backup capability. We believe this terminology to be confusing, especially when used in conjunction with the term differential backup, which is also considered a form of incremental backup. Additionally, some vendors may require the use of several available backup levels to implement differential incremental backup. For example, levels 4 through 9 may be needed to configure differential incremental backups on a Monday through Saturday schedule. With only three remaining non-zero backup levels, this may limit the number of ways that other lower level backups can be configured. Our True incremental Backup is implemented as a single Partial Cumulative Incremental (PCI) Backup level and any number of backup levels that may be configured with TiBS.

Three Types of Differential Backup

Direct Differential: A Differential Backup that copies Primary Storage on a target system to directly attached Secondary Storage on the target system.

Network Differential: A Differential Backup that copies Primary Storage on a target system over a network to Secondary Storage.

Synthetic Differential: A special type of Differential that will consolidate some or all of the Backup Volumes that have been created since the most recent full backup on the Backup System. This process is performed by a Backup System with no interaction with the Primary Storage on the target system. The resulting backup volume contains the same data as one that would have been taken from the target system for that period of time.

Additional Backup Volume Resources

Learn About the True incremental Backup System for Enterprise Centralized Network Backup

Three versions of the True incremental Backup System are available. All three versions employ synthetic backup consolidation technology to reduce the load on backup clients and networks. All three versions also have no per seat charges! Learn More ...