Fast incremental backup via Changed Block Tracking (CBT)

Information covered


Understand how the IDrive BMR device uses it's Changed Block Tracking (CBT) driver to perform fast incremental backup and optimizes the backup duration and the network bandwidth.


IDrive BMR allows you to perform bare-metal backup of your physical machines. By default, the first backup of a machine is a full backup and the consecutive ones are incremental. During a full backup, all blocks of data from the selected volumes are backed up to the device. In the case of a regular incremental backup, typically, the device checks every block of data and backs up only the modified blocks. IDrive BMR, however, uses the Changed Block Tracking (CBT) driver, installed on your computer via the backup agent, to identify the changed blocks of data. Incremental backup via CBT is faster when compared with the regular incremental backup, thereby making it possible to have a shorter backup interval. You can also force a full backup at any time.

Note: The first image backup that is initiated on the BMR device is always a full image backup. If you force a full image backup the second time, a synthetic full backup is performed to save time and storage space.

BMR’s Changed Block Tracking driver

What does the Changed Block Tracking driver do?

IDrive BMR leverages its own Changed Block Tracking (CBT) driver to backup only the modified blocks of data since the last backup, rather than backing up every block of data in the physical machine. 

How does the device identify modified blocks of data during backup?

The CBT driver tags modified blocks, marking them for backup. During an incremental backup, the backup agent uses these tags to identify the modified data blocks that need to be sent to the BMR device for backup.

How does the CBT feature add value to the user experience?

The CBT feature reduces the volume of the data undergoing backup, thereby increasing the backup speed and reducing network utilization.

Note: CBT is enabled by default.

Operating systems compatible with Changed Block Tracking driver

The CBT feature is supported for most latest operating systems. It is not supported for certain older operating systems such as Windows Vista, Windows Server 2008, and the 32-bit version of both Windows 7 and Windows Server 2008R2.

In the case the operating system is not compatible with the Changed Block Tracking driver, the regular incremental backup is performed.