In addition, USB support over an RDP session has been further enhanced such that if a device works locally on
the Windows client, it will work over an RDP session with no special drivers required. Previously, only a small
subset of Windows-compatible USB devices could be "sent" over an RDP connection, making the VDI deployment choice
limited for shops where users have a lot of local peripherals. Smart card readers, webcams, games and so on work
seamlessly as long as a driver is available to the local client -- the remote process is all taken care of by
There is also a new "Fair Share" technology that manages the allocation of CPU, memory, disk space and network
bandwidth among all running sessions on a host. It prevents one user from hogging resources and limits users to a
certain percentage of available resources.
You can configure caps on each of the items globally and then those percentages are applied evenly across all
running settings. You can't specify that one user can have twice as much network space as another by default, for
example, which is why the technology is known as Fair Share. But it's a good way to ensure one user doesn't degrade
the VDI experience for everyone by streaming a high-definition movie.
In addition, a big disadvantage of the pooled desktops has been removed. In the past, when users were assigned a
pooled virtual machine, they had a degraded experience. Whenever they made changes to preferences, settings or
saved data locally to the pooled machine, those settings were destroyed upon logout since the pooled image remained
static. (This didn't apply to personal virtual desktops that were preserved individually for each user.)
In Windows Server 2012, the operating system will now create a separate virtual hard disk (VHD) file that stores
user personalization information. When users log in to a pooled desktop, Windows will stream this personal VHD
alongside the pooled image VHD to create a personalized experience. It also preserves any changes to the user disk
and saves it so that the next time a user logs in, those changes are streamed back in.
Now you get the benefit of patching and maintaining a single image while allowing users to customize their work
environment as if it were their own.