One of the new features in vSphere is the ability to track which blocks changed between backups. This is useful for the new generation of backup software that is capable of performing a disk-level backup of a VM, and now can perform incremental backups. So, how do you enable it without manually editing all your VMs?
The post at http://xtravirt.com/powercli-enable-changed-block-tracking has information on enabling and identifying if tracking is enabled on your VMs
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