Patent attributes
A method for backing up virtual machine (VM) data is described, and includes determining a disk layout of a VM disk associated with the first VM to be backed up, the disk layout having a plurality of nodes in a hierarchical structure, each node corresponding a VM, and traversing the VM disk layout to identify one or more parent nodes with respect to a first node representing the first VM. The method further includes, for each second VMs that is related to the first VM as a parent node, determining whether the second VM has been previously backed up by examining a predetermined tag. If the second VM has not been previously backed up, then back up a list of changed blocks representing a difference between the second and third VMs. Otherwise, back up the second VM and tag the second VM to indicate that it has been backed up.
