PHD Virtual Backup for VMware vSphere

PHDVB User Guide > PHD Virtual Backup Overview > Changed Block Tracking

PHD Virtual Backup and Changed Block Tracking

VMware's Changed Block Tracking (CBT) reduces both the backup window and storage requirements for your backup jobs. With PHD Virtual Backup, you can take advantage of VMware's vStorage API and enable Changed Block Tracking at the job level to reduce the time your backups take and the amount of data sent to your backup storage location.

When CBT is enabled for a backup job, each VM in the job is checked to see if it is hardware version 7. If the VM meets this requirement, the CBT configuration parameter (ctkEnabled = true) is enabled for that VM the first time the job runs. The initial backup that takes place with CBT enabled reads all blocks of the VM's virtual disks to create a change ID for the VM. The next time the backup job is run, the change ID is used to determine only the blocks that have changed since the last backup for each VM. Only the changed blocks are then included in the backup.

CBT Notes





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