Does the VMware Plugin backup the entire virtual machine hard drive? (4035140)

For more information on this topic, please see the Module 4-Advanced Administration Part Two-Web-based Training

The size of a Virtual Machine (VM) backup can vary and may not be the exact size of the VM disks being backed up.
If a VM is configured with thin provisioned disks, the backup could be smaller.
Also the use of Change Block Tracking (CBT) and Active Block Mapping (ABM) can also reduce the size of a VM backup.
The current VMware Plugin User Guide explains how CBT can reduce the size of VM backups:

https://support.quest.com/search?k=NetVault+Backup+Plug-in+for+VMware+User%27s+Guide+configuring+cbt

“The Changed Block Tracking (CBT) feature allows virtual machines to keep track of changed disk sectors. This feature is available to virtual machines that are managed by ESX/ESXi 4.0 or later. When CBT is enabled on a virtual machine, a “Change ID” is assigned to each disk during the snapshot generation activity. The Change ID identifies the state of a virtual disk at a specific point in time. Subsequent snapshots capture only the blocks that have changed since the last snapshot. CBT offers the following advantages:

• It allows Incremental and Differential image-level backups of virtual machines.  
• It often reduces the backup size of Full image-level backups because only the used sectors of a virtual disk are backed up.  

CBT is only supported on virtual machines that use virtual hardware 7 or later. CBT is not supported on virtual machines that use Physical compatibility RDM virtual disks, Virtual compatibility RDM (Independent Disks), or Virtual disks attached to a shared virtual SCSI bus".

Further information is in Chapter 4 – Image Level Backups section within the VMware Plugin Users Guide on the following link:

https://support.quest.com/search?k=NetVault+Backup+Plug-in+for+VMware+User%27s+Guide+Image+Level+Backups