Meeting VDI Challenges: Yesterday, Today and Tomorrow

A July 2010 CIO Technology Priorities Study by IDG indicated the number one interest - cited by 45 percent of respondents - of CIOs was “Virtualization, Desktop PC”, otherwise known in the vernacular as VDI.

Interest eventually translates to implementation, and over the past year we’ve seen increasing deployments of VDI (virtual desktop infrastructure) across a variety of organizations. We’ve also seen many challenges faced by those organizations attempting to implement a reliable and scalable VDI. Dynamic scalability, new and sometimes unsupported protocols, poor end-user performance; these often frustrating obstacles threatened the success of VDI rollouts, especially in large organizations.

Initial VDI Challenges

Initial rollouts of VDI encountered many challenges, most of which turned out to be delivery issues. High on the list was the stickiness of VDI sessions, requiring a more intelligent and aware delivery infrastructure capable of maintaining persistent connections to specific VDI servers while simultaneously managing load in a way that did not incur significant performance penalties. This was critical because performance was – and remains – a significant sticking point for VDI. End-user adoption and acceptance is highly dependent on PC-like responsiveness from virtual counterparts and any degradation can be disastrous to the success – perceived or actual – of a VDI rollout.

Compounding the performance issue was the introduction of a new protocol, PCoIP (PC over IP). PCoIP was originally targeted to improve performance of rich media delivery, but also proved useful in improving performance over long distances, such as the distances over which remote and roaming end-users access corporate resources using an SSL VPN. While PCoIP improved performance, wrapping a connectionless protocol in a connection-oriented security protocol proved to be an impediment, slowing down delivery and making virtual desktop usage highly frustrating for end users. The DTLS (Datagram Transport Layer Security) protocol solved this issue neatly, but was nearly thwarted by the issue of support (or, more properly, lack thereof) by secure remote access vendors.

The need for secure access, however, reintroduced problems with stickiness, as intermediaries responsible for load balancing VDI sessions were unable to match up users with servers, wreaking havoc with delivery. This model also proved to incur additional performance problems due to the extra burden it placed on VDI servers, resulting in a lowered density and higher cost to scale. Delivery infrastructure capable of terminating DTLS and leveraging hardware proved to alleviate the performance degradation and resolve the issues with stickiness.

These potential show-stopping obstacles were eventually overcome by a collaborative architectural strategy comprising virtualization technology and traditional infrastructure. Application delivery infrastructure provides persistence-based application routing to ensure end users, once connected to their virtual desktops, continue to be connected. Hardware-assisted cryptography in application delivery infrastructure ensures optimal performance for the secure transport of virtual desktops inside and outside the data center.