Hybrid Desktop Virtualization: A New Approach for the Cloud

By Issy Ben-Shaul (Profile)
Wednesday, May 11th 2011

Desktop virtualization (DV) is a big technology trend, but despite the number of approaches taken by entrants to this new market, there are few solutions that are well suited for use in the cloud. Take for example, the Virtual Desktop Infrastructure (VDI) approach, which allows users to connect any device to the data center using remote desktop protocols. That works great for task workers and thin client devices tethered to the LAN, but it is not ideal for users who work offline, distributed users who connect to the data center over the WAN or mobile power users running demanding multimedia applications. Laptops, in particular, present unique management challenges, since they are often used offline or outside the corporate network.

Client-hosted desktop virtualization tries to address the needs of mobile and distributed users by executing the desktop on a virtual machine at the endpoint, combined with some central management of the desktop images. However, a hypervisor-based solution can create performance, security and support problems. If the host OS is not operating properly, the VM will be impacted. Moreover, with a type-2 hypervisor, the underlying host OS is unmanaged, requiring external means to manage it, as well as the additonal expense of OS licenses. Type-1 hypervisors eliminate the need to manage and the expense of two OSes, but offers very limited hardware compatibility, especially for laptops, which come with a myriad of peripheral devices.

A New Hybrid Solution to Desktop Virtualization

Today, new hybrid desktop virtualization solutions are emerging that combine the centralization and manageability of server-based DV with the flexibility to work offline on a fully personalized laptop. Each user’s complete desktop image is centralized in the public or private cloud, so it is protected and can be more easily managed by an IT department or managed service provider. Comprehensive tools for image management are also a key advantage, allowing IT administrators to simplify updates and patches while increasing endpoint stability. However, end users execute an instance of this central desktop locally on their PC without a hypervisor. This gives users native performance, with the flexibility to install applications, work with multimedia apps, handle bi-directional apps like video and audio conferencing, and to work offline.

With many desktop virtualization methods, an image update wipes out all personalization a user has added. Hybrid desktop virtualization implements image layering which allows IT to update the base image layer that is often comprised of an OS and centrally-managed applications like Office without overwriting layers contributed by the user, such as user-installed applications or user data and settings. Such decoupling of the image into independently managed layers requires the system to operate at the file-system level and be file-aware, as opposed to traditional desktop virtualization solutions that operate at the block-level which can’t easily segregate and merge user-installed applications and data from centrally managed images. 

Asynchronous communication is also important otherwise, the end user must constantly be connected to the network. With an asynchronous model, when an endpoint is connected to the network, the system synchronizes continuously with the data center. However, when the endpoint is disconnected (or perhaps even connected to the Internet but not connected to the WAN) the system continues to work seamlessly, with all changes recorded. When the user re-connects to the network, changes made by the administrator to the centrally managed desktop propagate to the endpoint, and changes made by end users to their PC propagate to the data center.