To achieve the highest level of data deduplication, a Guest-level backup is the recommended method. This involves installing the Avamar agent directly inside the guest operating system of the virtual machine. The agent operates at the file level, intelligently identifying and backing up only used data blocks while ignoring empty space, temporary files, and swap files. This file-level awareness allows Avamar to find more commonality across different VMs (e.g., shared OS files and applications), resulting in superior deduplication rates compared to image-level methods that process the entire virtual disk block by block.

A. ESX Console backup is not a standard Avamar backup method for virtual machines.

C. vSphere Image backup is an image-level method. While efficient, it typically yields lower deduplication rates than in-guest backups because it processes the entire VMDK.

D. VCB Image is an outdated VMware backup framework (VMware Consolidated Backup) that has been replaced by VADP, which is used by vSphere Image backups.

1. Dell Avamar 19.9 for VMware User Guide, Page 18, "Guest-level and image-level backups". The document states, "Guest-level backups can provide higher deduplication rates than image-level backups because the backup occurs within the guest operating system."