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Nutanix and SimpliVity's hyper-converged infrastructure products are a great match for VDI as both have scale-out, building block architectures. Nutanix has been in the game longer and offers customers more assurances on cost and performance, but SimpliVity can support the most virtual desktops per node.
Virtual desktops are the ultimate scale-out workload, featuring many small virtual machines (VMs) that together form a huge total resource requirement. Hyper-converged infrastructure (HCI) is software-defined and combines network, storage, compute and virtualization resources all in the same package, allowing administrators to scale their VDI deployment up by simply adding another node to the system.
The other close alignment between hyper-converged systems and VDI is the use of solid-state storage (SSS) to accelerate disk performance. VDI carries a demanding storage workload and is a good fit for the type of storage tiering that HCI products offer. Tiered storage moves the most frequently read storage blocks to a high-speed tier -- which often uses SSS -- to improve efficiency.
SimpliVity and Nutanix's HCI offerings share superficial similarities, but there are differences in their architectures and capabilities.
Nutanix and SimpliVity storage basics
There are a couple of storage challenges with VDI, mainly the capacity to hold all the desktops' disks and the storage I/O performance to avoid problems such as boot storms. If an organization wants to use virtual desktop clones from a parent VM, it needs the capacity to independently store each clone's OS and applications, which can quickly add up to terabytes of storage capacity.
One of the great features of Simplivity and Nutanix's HCI products is that adding nodes improves storage performance, because it adds resources to run more desktops, enabling linear scalability. Both vendors use an x86 server as a hypervisor node, and the nodes contain hard disks and SSS, as well as plenty of CPU and RAM. A collection of these nodes forms a cluster that provides both storage and compute resources, so the cluster should include enough nodes to handle an organization’s VM workload. If a single node can support 150 task worker virtual desktops, then four nodes will support 600 and so forth.
Both vendors' HCI offerings include capacity efficiency features such as data deduplication and compression to overcome storage challenges, and Nutanix offers erasure coding. These features enable efficient storage of full clone VMs without any operational changes. A deployment of 600 virtual desktops can easily require 10,000 storage IOPS, which is far in excess of what hard disks can deliver -- SSS is the only practical way to deliver the required performance.
Ultimately, the tiered storage approach in Nutanix and SimpliVity products with some SSS and some hard disk storage balances capacity, cost and performance.
Simplivity vs. Nutanix is a battle of density
Despite storage similarities, these two products differ when it comes to density.
Nutanix supports VDI with compute dense nodes that pack four hypervisor nodes into a 2U chassis. This allows VDI shops to deliver around 600 virtual desktops per 2U enclosure, so Nutanix provides great density for situations where data center space is expensive. Nutanix has reference architectures and customer references for tens of thousands of desktops using hundreds of Nutanix nodes. The company also offers VDI Assurance, which means Nutanix will provide extra server and storage hardware at no cost if it's not meeting the requirements of the service-level agreement.
The unique selling point for SimpliVity, on the other hand, is the data efficiency of its OmniStack HCI platform, which includes a Peripheral Component Interconnect Express card in every node that improves SSS performance with its point-to-point architecture. Data deduplication and compression is built into the SimpliVity platform -- admins cannot turn those features off -- to improve performance and capacity.
However, SimpliVity does not attempt to scale to the vast numbers of hypervisor nodes that Nutanix favors. Instead, Simplivity's platform offers a choice of 2U servers: Cisco, Lenovo or its own brand of servers. Benchmark results using Login VSI performance-testing software showed 250 task users on a single node, which is almost twice the number of users per node of any other published result. That means a four-node SimpliVity cluster can support 1,000 task workers. Organizations can manage an environment of up to eight of these desktop clusters -- or roughly 8,000 virtual desktops -- together. This VDI density is still new for SimpliVity, however, so it does not yet have a reference architecture.
Hyper-converged infrastructure is a great choice for VDI. Scaling the storage capacity and performance together with the compute capacity means no performance surprises. The SimpliVity versus Nutanix rivalry should heat up as more enterprises discover the benefits of using HCI. Nutanix has a longer track record of supporting VDI deployments from small to massive scale, but SimpliVity has pulled a surprise move with its amazing VDI density numbers.
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