Design and Implementation Overview

On vSphere, backups are usually done by taking a snapshot, to efficiency obtain a static image of the virtual machine. Snapshots are a view of a virtual machine at a certain point in time, and enable quick and clean backup operation. Snapshots also provide an incremental backup mechanism called changed block tracking.

To back up virtual machines on vSphere, VMware recommends a two-language solution. First use Java to code the backup program that contacts the host, takes a temporary snapshot, records virtual machine configuration, and (later) deletes the snapshot. Then use C++ or C to code the VDDK program that transfers virtual disk data from the snapshot to backup media.

For restore, VMware recommends a two-language solution. First use Java to code the program that instructs the virtual machine to halt, or re-creates the target virtual machine from recorded configuration. Then use C or C++ to code the VDDK program that transfers saved data from backup media to virtual disk.