When thinking about modern VMware backup solutions, most leverage a technology called Changed Block Tracking or CBT to facilitate taking incremental backups of virtual machines. This technology is derived from the VMware Data Protection API which allows third-party backup applications to take advantage of CBT to perform backups. The advantage of VMware CBT is that it significantly reduces the amount of time the backup software takes to perform incremental backups because it tracks changes in a special Changed Block Tracking log file. VMware Changed Block Tracking not only benefits incremental backups but also all related activities such as replication. Changed Block Tracking is also used by VMware’s Storage vMotion process that allows virtual machine disk files to be moved from one datastore to another while it is running. Let’s take a closer look at how Changed Block Tracking works, requirements for CBT, how to enable it, and how it relates to third-party backup utilities.
Written by NAKIVO
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