Hyperconvergence and OS


In the good old days (rose-tinted spectacles required), there was only one operating system in the stack. It took care of device drivers and file IO. There were many flavours of OS, depending on the period, from UNIX and Windows to OS/2 and MacOS, and many, many others. Over time, the selection of operating systems in the data center reduced down to Linux and Windows (there are still holdouts for others, for various specific reasons, but Linux and Windows hold about 90% of the OS market). There are many flavours of Linux, but all an app developer in the enterprise really needs to know is which OS they are targeting. More and more, even that level is too low down for the app developer who is looking more at the middleware to make the final decisions.

In the age of virtualization and cloud, deciding on an OS—which version of Windows, which flavour of Linux—is a matter of choosing à la carte from a menu of preconfigured options. This ability to choose the OSthe ability to run a VM, evenis dependent upon the availability of a hypervisor, a sub-OS that runs the virtual machine, that runs the OS.

In the hypervisor space, again, there is choice. Windows (Hyper-V) and Linux (OpenStack) have their place, but we also have VMware, probably the most widely installed hypervisor. The popularity of VMware’s ESX can be seen as soon as we look at the hyperconverged space. Hyperconverged systems split fairly neatly into two camps. Most hyperconverged systems are sold as a complete system. Even VMware’s VxRail system is sold as a bundle, including the hardware, although most of the components are sold separately. The systems also include quite a bit of “glue” code. This glue code holds the system together and makes adding extra nodes or configuring settings across the whole cluster much easier. Usually it takes care of installing the hypervisor to each system and adding the system to the cluster, as well as configuring the storage and management networks. In the case of SimpliVity, the glue code also adds the required drivers and OmniCube VMs that support the added hardware that makes SimpliVity unique. This glue code is what separates a hyperconverged system from a cluster of servers with VSAN (although a cluster of servers with VSAN or something similar certainly is very useful).

Looking at the market, we see three camps of hyperconverged systems. The first is those based on VxRail (and before it, EVO:RAIL). These are very obviously tied directly to ESX, as VxRail is very much a product of VMware. EMC’s VSPEX Blue is an example. HP and Supermicro also sell VxRail-based systems. Most recently, Dell has started to produce VxRail hardware, which makes sense with the ongoing merger. The next is those that are very much hardware with software added in. SimpliVity (owned by Dell) and Nutanix fall into this camp. They sell complete systems with hardware and software bundled. The final camp is the pure software system. It could be argued that a VMware implementation with VSAN is a “build-it-yourself” approach to hyperconvergence. However, without the glue, it misses many of the features. A similar build-it-yourself approach could be taken with OpenStack or Hyper-V. There are some companies out there selling products that contain the glue code. They are not getting a huge amount of traction. One of the attractions of hyperconvergence is that the system stands up quickly and is very easily repeated—modular, even. That is not the case with the pure software systems to the extent that a combined hardware/software approach is.

Looking at this, the vast majority of the hyperconverged market is tied into ESX. Hyperconverged is a relatively new market, so focusing on the leading hypervisor first makes sense. Nutanix made a nice niche by being hypervisor-agnostic. SimpliVity did so with its hardware acceleration. In recent weeks, SimpliVity has announced support for Hyper-V. This marks a distinct maturation point. The system as the glue layer must have been rewritten to include the very different ways of working with Hyper-V, not to mention the device drivers for its secret-sauce hardware. It also shows a maturation of the market as the vendors start to move out from their core products and explore other avenues. This new level of choice is vital as the data center moves forward.

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Anthony Metcalf
Anthony Metcalf (vantmet) has been in IT for over 10 years, working with UK firms in industries from Engineering to Law, along with service providers. Anthony works in all areas of the data centre, from networking to automation, and has recently been blogging the VCP-NV experience at
Anthony Metcalf

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