A recent post by William Lam on the VMware vSphere Blog clarifies in what scenarios the zero downtime really applies. It is worth being fully read, but for readers who are always in a rush (or have a too short attention span ;-) I will wrap it up in a few bullet points:
- It works for Windows guests only, starting with Windows Vista
- If device drivers that are needed for booting (Display, vmscsi, pvscsi) are updated then a reboot is still required
- KB2015163 explains in detail if and when a reboot is still required after updating the Tools in a Windows VM
Please note: Given the fact that device drivers are rarely updated this is still a great progress compared to the pre-5.1 VMware Tools that would always require a reboot after an update!