Enabling or Disabling Changed Block Tracking for Nutanix AHV IntelliSnap

Nutanix AHV CBT is an optional mechanism that enhances the backup performance of Nutanix AHV virtual disks. When you enable CBT, the incremental backups will read only the allocated and modified portions of virtual disks.


  • Nutanix AHV CBT is supported for streaming, backup copy and IntelliSnap operations. If IntelliSnap is enabled along with CBT, the backup copy job will use the CBT mechanism for incremental backups.
  • By default, the Read-Ahead Cache feature is enabled. With this, data from Nutanix AHV disks is loaded into memory before it needs to be read. If you choose to enable CBT, the two features work together to enhance the backup performance of Nutanix AHV virtual disks.
  • Both application-consistent snapshots and crash-consistent snapshots are supported.
  • When the retention rule for backup copies is set to spool copy, for Nutanix AHV CBT, one snapshot per VM will still be retained for comparison purposes.


  • Cluster environments must be Nutanix AHV Version or later.
  • If you are using V3 API: To run backups, your user account must have admin permissions (super user) with all roles defined, or you must configure AD services and then map the AD user account to the Cluster Admin role and Self Service Portal admin roles via their Self Service Portal. For more information, contact Nutanix Support & Services.


  • Nutanix AHV CBT does not support differential backups. If a differential backup is selected with CBT, the VMs will be protected with full backups.


  1. From the CommCell Browser, expand Client Computers > virtualization_client > Virtual Server > instance > backup_set.
  2. Right-click the subclient, and then click Backup Options.
  3. To enable the feature, select the Use Changed Block Tracking option, and then click OK.

    To disable the feature, clear the Use Changed Block Tracking option, and then click OK.

For more information on viewing CBT status, see Viewing Changed Block Tracking Status for Nutanix AHV IntelliSnap.

Last modified: 8/28/2018 12:54:38 PM