VMware – Changed Block Tracking

This is just a brief post for my own reference. A friend of mine had some backup problems on a VM recently. Seems they were using VMware’s Changed Block Tracking (CBT) and had since added a physical-mode RDM to the VM. This caused problems and things stopped working. The quick solution was to clone the VM and delete the stale data. I’m sure there’s a more thorough solution. But I don’t like to scratch the surface too much. CBT has been around a while, and is a pretty nifty feature. The VMguy has a good post on CBT and how it works. Duncan has a bit more info. And VMware themselves have some useful KB articles here and here.