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Although many organizations are still wary of the upfront price tag of hyper-converged infrastructure, VDI shops need to consider long-term operational savings when adding up the total cost of ownership.
Deciding to deploy VDI often causes IT to create a new virtualization infrastructure silo, because VDI is different from server virtualization. Keeping the company's VDI workload separate from the server virtualization workload is common practice. In larger deployments, IT can even use a separate architecture for VDI, such as hyper-converged infrastructure (HCI), which combines compute, storage, networking and virtualization resources all in one software-defined appliance. Similarly, converged infrastructure (CI) tightly integrates those same data center components, but without the software.
Before investing in hyper-converged appliances, though, IT needs to evaluate HCI products for their technical fit and decide if the total cost of ownership (TCO) is palatable. The silver lining with HCI is it simplifies IT management and makes it quick and easy to scale out a VDI deployment.
Save on deployment and updates
One core attribute of CI and HCI is a short time to value. Many organizations are able to deploy hyper-converged appliances on site over the course of hours or days. IT won't need to invest weeks into integration and systems testing, because the vendors take care of that. The result is that CI and HCI products require far less effort to deploy than mixed vendor offerings. Fiscally, this translates to a shorter and lower-cost project for IT to build a VDI platform.
In addition, periodic software updates are a fact of life in IT, and some HCI vendors even automate updates to their platform and hypervisor. This simplified management leads to a lower maintenance cost compared with custom-assembled infrastructure.
Take the pain out of shopping
Another key benefit of converged or hyper-converged appliances is simplicity of purchasing. Rather than selecting from thousands of parts to put together an infrastructure to support virtual desktops and applications, HCI vendors such as Nutanix and SimpliVity usually give companies less than a dozen hardware options. Each option is for a fixed-size deployment. IT can choose any option and know in advance that it works together and how much of each resource it's getting.
The flip side of this simplicity is that organizations sacrifice the endless customization options that are possible when building a data center from parts. Shopping for infrastructure components separately allows IT to choose from several hardware manufacturers, many of which customize their products for individual customers. With CI and HCI products, IT must select from a smaller range of options from a single vendor, and the available size options don't always align with every company's requirements.
Don't forget about scalability
When choosing the back-end hardware and software for VDI, organizations need to find the right match to support the initial VDI population and the expected growth, or contraction, in users. One of the ways CI and HCI suit VDI well is that both use a modular, building-block architecture. An enterprise-scale VDI deployment is usually made up of a number of identical, smaller appliances that each support one or two thousand desktop virtual machines.
The downfall of converged infrastructure is that it's limited to fairly large-scale deployments, and paying for more CI capacity than an organization needs will spoil the TCO. The smallest CI systems usually support at least 500 virtual desktops, and larger sizes can support as many as 4,000 desktops. In short, CI isn't a great value proposition for companies that only need to support 300 or fewer virtual desktops. In addition, to scale out a VDI deployment, IT has to buy large units that often include excess capacity.
Hyper-converged appliances go by much smaller units of scale, typically as low as a single physical server that supports 100 or so desktops. This allows IT shops to purchase only the resources they need, which is a huge financial benefit in slow-growing VDI deployments. HCI customers can just as easily deploy larger collections of nodes at one time to support faster growth.
Making the final decision
One downside of HCI is that some offerings do not include the required networking capacity, while CI usually comes as a complete infrastructure in a box. It isn't hard to deploy the 10 GB Ethernet networks necessary for HCI, but it's another task to complete and might require a high-priced engineer.
The simplicity of procuring, deploying and growing converged and hyper-converged platforms make them excellent options for isolating a VDI deployment from existing server virtualization infrastructure. CI is suitable for large-scale VDI or medium-scale deployments with little expectation of growth. HCI is usually a better fit for smaller VDI deployments and allows maximum flexibility for growth.
Converged and hyper-converged platforms aren't a fit for every organization, especially if the virtualization infrastructure in place already does the trick. Many IT shops will find, though, that CI and HCI products are relatively easy to shop for, simple to scale out and less complex to manage, saving businesses on long-term operational expenditures and making the TCO for HCI more acceptable.
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