A quick trick here to enable the disk performances view in the new task manager since Windows Server 2012.Indeed, in Windows 8/8.1, by default, you can see the disk’s performances, with usefull informations as read/write speeds.
In Windows Server 2012, by default you get :
To get the disk view, you have to enable it with that command :
Note : You need administrator permissions.
Once enabled :
You need to do this one time, it persists after reboots.