There are two primary ways hyper-converged infrastructure players package their products for sale: the hyper-converged software is sold on its own, or the software is wrapped up in hardware as an appliance. The latter is what we see from leading players Nutanix and SimpliVity. Neither of these vendors sells its software without the servers to run it on. But many other vendors -- such as Maxta, SpringPath and VMware -- offer their hyper-converged software so it can be installed on a customer's choice of servers.
Vendor motivation for the appliance approach
One significant post-sale expense for hyper-converged vendors is the support required to ensure customers have a good user experience. Support costs also cover software updates and patches that are released over time. Each software version, new patch or update needs to be tested on supported hardware platforms before it is released. With four or five current models, and a dozen past hardware models, testing will take time and cost quite a bit. The same complexity arises when customer issues need to be recreated in the support lab due to the challenge of mixed clusters, where half the hosts are from one vendor, and the others are from a competing hardware vendor. Custom hardware configurations are difficult for software-only, hyper-converged vendors to validate. Selling hyper-converged software wrapped in hardware reduces support and testing costs.
Why offer software-only?
Buying hyper-converged platform software separately from hardware will suit different types of customers:
- Those who already own servers. The storage array may be coming to the end of its life, but the servers are only a year old. The option to add storage to the existing servers and deploy hyper-converged software may be very attractive.
- Those who want to choose the exact combination of parts in their hyper-converged infrastructure. Appliance vendors usually have a limited range of hardware options -- typically, no more than six different models. Customers who want to select their own collection of parts will have a far greater choice with a software-only, hyper-converged architecture. For example, the administrator of a virtual desktop infrastructure platform may need a server with enough memory to provide adequate performance.
A vendor's decision to sell a software-only, hyper-converged option may also be based on its business model. For example, while VSAN is growing fast for VMware, it is still a small part of the overall business. The company is therefore unlikely to sell vSphere and VSAN on its own badged hardware. Instead, VSAN is sold as a bundle by hardware partners that integrate the VSAN software with their hardware. Atlantis Computing takes the same approach with its hyper-converged software -- it can only be purchased preinstalled on partner hardware.
Downsides to the software-only approach
If you choose to deploy an infrastructure based on a software-only, hyper-converged infrastructure, you will need to take a lot of care with the hardware. Always ensure the hardware selected is on your hyper-converged vendor's hardware compatibility list. But be aware that items can be removed from a vendor's hardware compatibility list. For example, storage adapter queue depth was identified as a problem during a cluster rebuild, so VMware removed many host bus adapters from its VSAN compatibility list. What does this mean for customers who had bought the adapters when they were on the list? If they want support, they must now replace the adapters at their own cost.
In addition to checking the hardware compatibility list regularly, users need to own more of the testing process and pay extra attention to upgrades. A vendor testing dozens of hardware models will most likely be less thorough than a vendor testing only 10 models. It might be beneficial to have an infrastructure test lab where upgrades to the hyper-converged platform can be tested before being deployed in a production environment.
A key benefit of a hyper-converged infrastructure is not worrying about the underlying parts. Hyper-convergence abstracts the hardware and allows you to focus on virtual machines and their applications. A software-only, hyper-converged infrastructure may be more flexible, but does it sacrifice the simplicity offered by hyper-convergence? You must consider the value of wrapping software in consistent hardware before deploying hyper-converged software on your own hardware.
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