The VMware vSphere storage architecture enables VMware Consolidated Backup. Consolidated Backup provides a centralized facility for LAN-free backup of virtual machines.

As shown in VMware Consolidated Backup, Consolidated Backup works in conjunction with a third-party backup agent residing on a separate backup proxy server (not on the server running ESX/ESXi) but does not require an agent inside the virtual machines.

When the third-party backup agent initiates a backup of virtual machine storage, Consolidated Backup runs a set of scripts. The pre-backup scripts quiesce the virtual disks and generate snapshots. Once completed, the post-backup scripts restore the virtual machine back to normal operation. At the same time, it mounts the disk snapshot to the backup proxy server. Finally, the third-party backup agent backs up the files on the mounted snapshot to its backup targets. By taking snapshots of the virtual disks and backing them up through a separate backup proxy server, Consolidated Backup provides a simple and low-overhead backup solution for the virtual environment, and is less intrusive than running backups inside each guest virtual machine.

VMware Consolidated Backup
This image shows how Consolidated Backup works with a third party backup agent to back up virtual machines onto disk.