“Storage IO Controls – New support for per Virtual Machine storage reservations to guarantee minimum service levels.” Is listed as one of the new features of vSphere 6.
The new mClock scheduler was introduced with vSphere 5.5 and as you might have guessed, it remains the default IO scheduler in vSphere 6 (don’t mind the typo in the description).
Besides limits and shares, the scheduler now supports reservations. Let’s do a quick recap on resource management.