Citrix Delivers Multi-tenant VDI Service

Sridhar Mullapudi, Director of Product Management at Citrix Systems, took to the Citrix Blog last Friday to announced Server VDI is here! Deliver Multi-tenant Cloud hosted VDI desktops from the Cloud giving every appearance of being particularly pleased with himself. As well he might.

We covered Microsoft’s difficulties in acknowledging the need for multi-tenant VDI hosting services earlier in the year when OnLive first introduced its multi-tenant SPLA-busting service, and later when it chose to appease Microsoft by swapping out its Windows 7 desktop licenses for SPLA-able Windows Server 2008 licenses. For its sins OnLive Desktop remains stuck at the starting gate, the promised Pro and Enterprise editions are still only promises, and both the product and terms of service remain unacceptable for anything except the most limited use. But OnLive’s lack of progress has not quieted the voices clamoring for a more service provider friendly VDI platform.

Now though, after watching the situation develop over the first half of the year Citrix has is extending the solution set available to service providers looking to implement multi-tenant DaaS offerings and has launched its own multi-tenant VDI platform.

It’s easy to get lost in jungle of products, technologies and marketing labels that Citrix presents, so to reduce confusion a quick recap of desktop virtualization products might help:


Citrix flagship product has offered Published Desktops along side Published Applications since day its earliest days when Citrix popularized Server Based Computing (SBC) with the introduction in WinView for OS 2. WinView was followed up by WinFrame which was based on Windows NT 3.5 which became the foundation of Citrix’s subsequent success. Citrix XenApp continues to deliver Published Desktops which Citrix now prefers to label “Hosted Shared Desktops” to distinguish it from “Hosted VDI” ( i.e., XenDesktop and VDI-in-a-Box). The most obvious difference between hosted shared and hosted VDI being that hosted shared desktops all run on a single shared instanced of Window Server 2008 R2.  Although to confuse matters slightly, Citrix does offer within XenApp a way to implement Published Applications running on a dedicated copy of a desktop operating system. Confusing, but a valuable service nevertheless where application vendors will not certify their product for use on a Hosted Shared platform.

XenDesktop and VDI-in-a-Box

These are Citrix’s “Hosted VDI” platforms, individual desktop operating systems all running on a virtual infrastructure, so that no part of the desktop operating system is shared between users.

Because XenApp is implemented on a shared server OS, its is significantly more efficient when it comes to server resource utilization, supporting four or more times as many desktop sessions per server than can be delivered using XenDesktop or VDI-in-a-Box. Seven VDI can be seen as an extension of XenDesktop

Server VDI is an extension of XenDesktop, in reality no more than an minor update to the Virtual Desktop Agent (VDA) to allow it to recognize on Windows Server 2008 R2. Packaged as a new feature of the service provider only edition of XenDesktop. Service providers looking to implement Server VDI would do so using the SPLA of Windows Server 2008 R2 along with Remote Desktop Services Subscriber Access Licenses (RDS-SAL) for each user.

Mullapudi is quite clear on why Citrix has taken this direction making it quite clear that the only reason that Citrix has taken this action is because of Microsoft’s failure to offer a viable Windows 7 licensing agreement

This technology is only available for Service Providers who have been waiting for a way to get some of the benefits available with VDI, but have not had a cost-effective Microsoft SPLA-compliant option

Nor does he hide the fact that  it’s still going to be more expensive in terms of licenses and infrastructure than a hosted shared desktop, or conventional VDI with a desktop OS.  Offering that enterprise customers deploying VDI already have other options with XenDesktop VDI and VDI-in-a-Box. He’s less clear on the other shortcoming of offering a server OS in place of a desktop OS, naming the difficulty in getting application vendor support – no matter how closely aligned Windows server 2008 R2 is to Windows 7 there are many vendors who choose not to to support their applications on anything other than a desktop OS. Server VDI is therefore a far from ideal solution, but it does fulfill unmet need and they may be value in that.

The key question here is has Citrix taken this move after acknowledging that Microsoft is not going to adjust its position on Windows licensing, or is this a not so subtle message to Microsoft that it is about time it woke up to the reality of the situation and started offering Windows 7 in a way that service providers can. Citrix has a long and successful track record of blazing a trail for Microsoft, identifying and profiting from new application and desktop opportunities before the lumbering beast can catch up. The Citrix Microsoft relationship being not so much holding a tiger by the tail,as leading a bull by its nose. However, Microsoft’s history of following Citrix’s lead is no guarantee that it will offer its own equivalent solution this time. The writing has been on the wall long enough for even the most myopic to read it and this move may not be enough to adjust Microsoft’s puzzling intransigence on VDI licensing policy. Unfortunately, because Citrix is making Server VDI available as a feature of the current service provider edition of XenDesktop it will be impossible to get hard data on the number of desktops delivered this way, and Mullapudi declined to comment on the possibility that Citrix was attempting to apply pressure on Microsoft to change its VDI licensing policy for service providers. It will be interesting to see if VMware or Quest (now part of Dell) choose to enter this market alongside Citrix.  Both companies could adjust their VDI solutions to match Citrx’s lead with little difficulty if they thought that there was money to be made here.

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