In this paper, we introduce the world of Hyper-Converged Infrastructures (HCI) and help you determine if HCI is a good fit for your organization. We begin by explaining how HCI systems differ from traditional and converged IT systems both physically and operationally. We then explore the advantages of an HCI system and explain how it relates to other industry initiatives such as the Software Defined Data Center (SDDC), Software Defined Networking (SDN), Software Defined Storage (SDS), and Policy-Based Management (PBM). We conclude by looking at how an organization can benefit from HCI systems in a variety of situations.
If you have ever deployed equipment in a data center, you’re already familiar with some of the challenges. For everyone else, let’s review why adding equipment into data centers can go from a nice step-by-step list on a whiteboard to a frustrating experience with your hands stuck in a rack at two in the morning.
First, let’s discuss traditional systems in the data center: the racks of individual servers, storage arrays, and network equipment. These are discrete components typically sourced from multiple vendors or manufacturers. The server is made by one company, the storage by another, and the networking by a third company. The combinations of vendors and products seems nearly endless, which is what makes this model so flexible and desirable to many people.
This flexibility, however, is just an illusion. Realistically, due to nuances in the implementation or subtle differences in design, there are far fewer working combinations of these components than one would expect. The vendors themselves realized this problem and provide Hardware Compatibility Lists (HCL) to help customers determine which components work together. Unfortunately, not everyone reads these lists, and even those who do read them may make incorrect assumptions about seemingly innocuous things like firmware versions that later prove to be disastrously incompatible.
Even if you have a winning combination of products between your servers, storage, and networking, you will still face the challenge of performance bottlenecks. Even new systems may have a bottleneck on one of the resources, it just may be insignificant at the moment. As time passes, the bottlenecks become more pronounced. Yet in traditional systems, no single management tool exists to help diagnose or identify which component is causing the bottleneck. Troubleshooting turns into a game of chasing the weakest link in the resource chain until you finally upgrade nearly every subsystem.
To combat challenges in traditional systems, vendors began creating what are known as converged systems. These started as server-blade chassis and enclosures that include servers and networking equipment. Some later versions even include a pool of storage that can be assigned to servers. One of the best-known forms of convergence is via storage networking, specifically a storage protocol known as Fibre Channel over Ethernet (FCoE).
FCoE systems leverage special converged networking and storage adapters to allow servers to access Fibre Channel storage devices using a single set of Ethernet cables. The chief advantage to these converged systems is the ability to use very thin servers or blades to physically accommodate the number of hardware cards required to access external storage while still maintaining high speed access to the network.
While converged systems help reduce some data center cabling, they don’t necessarily reduce the complexity of managing the data center overall. With converged systems, it is still necessary to manage servers, storage, and networking as separate components even if the connectivity between them has been consolidated.
HCI systems are rack-mounted devices that are typically no larger than a 1U or 2U rack-mounted server (approximately 3.5 inches high in a standard 19-inch rack). They look like small servers, yet they also bear a resemblance to a miniature blade chassis. These devices often have many hot-pluggable modules in the front and back for things like hard drives and server blades. Depending on the make and model of the HCI system, the device may only be tethered to your data center by four wires: two power cables and two Ethernet cables.
HCI represents the third generation of systems intended to simplify data center management. In the next section of this paper, we will explore how HCI systems deliver on that promise.
The Advantages of a Hyper-Converged Infrastructure
Taking away marketing terminology, at the most basic level an HCI system is simply a machine containing all the compute, storage, and networking resources to host a set of virtual machines. It’s natural to wonder how this differs from every other server out there with local storage and a hypervisor. While an HCI system may look like a typical rack-mounted server, you won’t manage it in the same way. HCI systems vary by vendor, but inside, you will typically find one or more small form-factor blade servers, a shared storage system, a central management module, and an Ethernet switch that connects everything inside together and then exposes the servers to the outside world. Finally, these server blades boot to a hypervisor that hosts virtual machines stored on the shared storage system thereby creating a virtual data center in a box.
Part of that design may sound familiar. Vendors have been producing blade chassis units that provide similar functions for over a decade. However, blade server chassis are unable to solve the bigger picture problems of operational management. For that, we have HCI.