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The definition of hyper-converged infrastructure has always been a bit tricky.
HCI consists of traditional IT resources -- storage, compute, virtualization and sometimes networking -- packaged and managed differently than people are used to seeing. Industry analysts came up with the term mainly to describe what Nutanix was doing in 2011 when it launched what an early customer called "a mini data center in a box." That led to ad hoc attempts to come up with a definition of hyper-converged infrastructure to fit this new IT category, as converged infrastructure also emerged around the same time.
SearchConvergedInfrastructure defines hyper-convergence as "a software-centric architecture that tightly integrates compute, storage and virtualization resources in a single system that usually consists of x86 hardware. A hyper-converged system can also be sold as software that can be installed on a buyer's existing hardware or as hardware purchased specifically for the installation." So we have software-defined storage; commodity hardware; and tightly integrated compute, storage and virtualization, all characteristics that distinguish hyper-converged from converged infrastructure.
This definition also fits HCI from early players, such as Nutanix, Pivot3, Scale Computing, SimpliVity and VMware, as well HCI from server giants Cisco, Dell EMC, Hewlett Packard Enterprise (which acquired SimpliVity last year) and Lenovo.
HCI continues to evolve, however, as new players come in and expand the category. That's why a recent SearchConvergedInfrastructure.com buyer's guide article gave a general definition of hyper-converged infrastructure, describing it as a "data center architecture that either loosely or tightly couples servers, storage and a hypervisor." This opens the door for newcomers such as NetApp HCI and Datrium DVX, which don't tightly integrate servers and storage in one box. There is also Microsoft Azure Stack, which brings Microsoft software-defined storage and Azure Stack storage services into an on-premises configuration.
Do these products fit the strict definition of HCI? Not really. Can they confuse things? Yes. But they shouldn't, because they can fulfill the role of simplifying traditional three-tier architecture while including enterprise capabilities. And that's really the point of hyper-convergence.
These newcomers position their products as second-generation HCI, improving upon the early entries. Others would call them bandwagon jumpers, trying to take advantage of a hot trend.
NetApp repurposed its SolidFire all-flash technology into HCI after realizing it addressed many of the same use cases. Datrium resisted calling its DVX platform HCI until its executives realized HCI is growing far faster than the storage market as whole.
"HCI has been around long enough now that people have opinions," said Brian Biles, Datrium co-founder and chief product officer. "People have tried it; sometimes it's been successful and sometimes not. But as a marketing term, it is powerful."
In other words, HCI is here to stay, however it's defined. It may be a self-contained data center or the on-premises part of a hybrid cloud. Either way, HCI will remain at least as a building block for the foreseeable future and likely continue to evolve as long as it sticks to its core mission of making it easier to configure and manage storage in virtual -- and now containerized -- environments.
"Some folks say HCI is just a bridge technology to the ultimate cloud environment, where they think everything is going," said Steven Hill, a 451 Research analyst. "I'm not sure of that. I think that hybrid is always going to be the play. The big thing is to make it simple. People using HCI aren't rack monkeys who have been wrenching this stuff together over decades. The new consumers of IT service want it simple. They don't want to build things from scratch. They want to plug and play. And that's a lot of the power behind HCI."
So whether you're a fan of multi-cloud, hybrid cloud, private cloud or no cloud, there's a chance you'll be looking at fitting a product that falls under the definition of hyper-converged infrastructure into your data center.
HCI purchase considerations
When looking for a hyper-converged product, consider a few things:
- Staffing. Who will buy and manage this? Many organizations use HCI as a way for virtual admins and applications owners to provision their own storage rather than another piece of infrastructure for storage admins to manage.
- Scalability. Can you add storage capacity without compute and vice versa? What are the minimum and maximum nodes you can have in a cluster?
- Software-defined storage. How tightly is the hyper-converged-enabling software tied to the underlying hardware you're purchasing? Can you continue to use the software to manage your storage if you move to another hardware platform?
- Cloud. How does HCI tie into your cloud plans, particularly hybrid or multi-cloud?
- Storage management. Does the HCI system offer features found in most other storage products, such as data deduplication and compression, snapshots and replication, and all-flash configurations? And what are the HCI vendor's plans to support emerging technologies such as predictive analytics, AI and containers?
- Hypervisors Most HCI systems support the market-leading hypervisor, VMware ESXi. Others use open source hypervisors as an alternative and brag about how they save customers VMware licensing fees. A few support VMware and other hypervisors, such as Microsoft Hyper-V and kernel-based virtual machine (KVM). For instance, Nutanix has its own KVM-based hypervisor, called AHV, but continues to support ESXi.
- Support. This is especially critical for HCI systems that use software and underlying hardware from different vendors. Find out who you call for support and how the process is handled.
Expect these seven aspects of hyper-convergence to remain constant as the definition of hyper-converged infrastructure continues to evolve. Use them as guideposts when deciding what you want to achieve with HCI and as you start to compare hyper-converged vendors and products.
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