It seems the software-defined storage market is all about using commodity hardware to build out a data center....
However, most software-defined storage vendors tell you exactly what hardware to use. If the hardware is truly a commodity, then a simple minimum specification should be all that is required.
The reality is that x86 server hardware is not an undifferentiated commodity: Every model from each vendor has different components. The result is that each combination of components needs to be certified together for each hypervisor. Even standardized components like network and storage adapters may need to be certified with storage services.
The x86 servers that power modern data centers are often referred to as a commodity. The implication is that any server will do. In reality, this is not true. When a software-defined product vendor talks about commodity hardware, they are referring to an economic model rather than complete interchangeability. Many older storage systems that relied on custom hardware are hardware-defined. The array was built from disk shelves and controllers designed specifically for the storage array. These storage systems had a huge amount of hardware design cost and saw slow changes because physical manufacturing of sheet metal and custom ASICs both take a lot of time. Software-defined storage runs on standard servers that could run Windows or a hypervisor, but it's the software that turns this hardware into a storage array.
Control for performance
By tightly controlling both the hardware and software, the software-defined storage market can deliver an integrated experience to customers. Part of delivering this experience is limiting the cost of hardware certification. More combinations of hardware and software that must be tested means more cost and more time before a product can ship. Software-defined storage vendors commonly require the use of specific hardware that you buy from them. By restricting the hardware selection, a software-defined product vendor can control the cost of testing new software versions. Maximizing storage performance is about aligning the performance of every step on the data path. That means SDS vendors that want to extract the best performance also tune their software for the exact hardware components they choose. These vendors will choose specific network adapters, storage adapters and drives to align performance and ensure the array benefits from every component. This tight control is an essential part of high-performance storage.
Bring your own servers
Not all storage needs to be blazing fast. Many workloads suit storage with moderate performance and much lower cost. This segment of the software-defined storage market is much more amenable to customers using their choice of commodity hardware. SDS vendors targeting midrange performance and lower are likely to ship as software-only, rather than software wrapped in hardware. Today's moderate performance still provides far better performance than was achievable five years ago. The rise of low cost solid-state drives enables astounding performance in hybrid configurations.
Some software-defined storage providers want to deliver ultimate performance by tightly controlling every component. Other SDS vendors are able to deliver great performance using whatever hardware you choose. Both use commodity hardware to enable lower costs and speed innovation.
Complete guide to the software-defined storage industry
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