Here are four steps to ensure a successful VDI implementation:
1. Determine Need
"The first thing is to have a defined reason for making a move to virtualization," says Chip Timm, president at IT service provider TR Technologies. "Once that’s determined--be it eliminating energy usage, consolidation of systems, security, more consistent systems management or some other reason--it then needs to be determined if VDI is a feasible option over a terminal server solution or simply upgrading existing infrastructure."
That includes knowing what the line-of-business applications are and what desktop virtualization methods are supported, as well as user storage requirements and if there is a need to support a bring-your-own device scenario, he says.
To Bill Cassidy, CTO of data center technology consultant IT Partners, there are a few critical reasons for organizations to consider desktop virtualization.
"In general," Cassidy says, "we encourage customers to look at VDI technologies when one or more of the following conditions are present: planning a desktop OS upgrade (for example, Windows XP to Windows 7/8); a traditional desktop hardware refresh is upcoming or is past due; [or] other business drivers are posing challenges to the traditional desktop model. This could be anything from offshore development security concerns to PCI compliance to user mobility initiatives."
A non-valid reason would be because "everyone says, 'This is what we should do,'" he says.
2. Calculate Full Cost
Understanding the true cost of a VDI deployment is a common challenge organizations face, he adds, noting that far too often there is a belief that deploying VDI in lieu of a traditional desktop refresh must be less expensive. In many cases, this is due to a belief that a new VDI environment can be deployed alongside existing virtual server workloads--something that should be discouraged due to the differences in performance characteristics of desktop and server workloads.
Other times, failing to fully understand the costs of all products, licenses, training and other expenses associated with VDI projects leads to costs being underestimated, Cassidy says.
The cost of storage, particularly expensive SANs, has been the single largest reason enterprises have been sluggish in adopting VDI, says Shaun Coleman, VP of products at CloudVolumes. Shared storage or a SAN may actually not be needed; instead, organizations could use local attached SATA or PCIe SSDs in their hypervisor.
[Find out ways to provide a rich desktop experience but not get crushed by storage costs with your VDI rollout in "Solving VDI Problems with SSDs and Data Deduplication."]
"Use of non-persistent desktops and solutions … that allow you to have a single copy of an app shared across all users allows for the use of inexpensive high-speed direct attached SSD," he says. "With inexpensive high-speed local storage and server class CPUs, end users may in fact get better performance than they would have had on a physical desktop. Shared storage can then be used only for those user-specific things needing a highly reliable storage fabric, such as their documents and settings."
3. Understand Network Requirements
Many organizations make the mistake of "diving head first into VDI" without considering how users will access their VDI instances over the network, Coleman warns. This makes it very important for enterprises to size their networks correctly, he adds.
"Bandwidth is not the most important consideration; latency is the killer," he says. "Enterprises should size their network for VDI similar to how they have deployed VoIP, whereby the user’s phone was near to the PBX and had a relatively low latency connection (sub 100ms). Endpoints and VDI instances should be accessed, if at all possible, over a LAN and within a relatively short distance from the servers/hypervisors running the virtual machines."
4. Conduct Thorough Planning
As with most IT projects, a successful VDI deployment becomes more likely if adequate time is spent in the assessment, planning and design phases, notes Cassidy.
"Poor design can include mixing desktop and server workloads, storage designed without an understanding of desktop I/O requirements and behaviors, networking issues including LAN and WAN bandwidth constraints--the list is practically endless, and most [issues] truly cannot be mitigated without a proper VDI assessment," he says.
Beyond the challenges with the supporting infrastructure, organizations can run into problems if they don't understanding their complete desktop application catalog, he adds. Most midsize and larger organizations have dozens, if not hundreds, of applications on desktops, he says.
"Will all of these accept the virtual hardware platform presented by the VDI solution? Can they be packaged using an application virtualization or packaging tool, if that is also part of the VDI solution? Add to the mix applications with local PC hardware dependencies, USB or parallel port key dongles, innumerable varieties of local printers and other peripherals, and it can get ugly quickly," he says.
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