The Five (and soon to be Six) Classifications of All-flash Arrays

The all-flash array market has settled down considerably in the last few years. While there are more all-flash arrays (90+ models) and vendors (20+) than ever before, the ways in which these models can be grouped and classified has also become easier. As DCIG looks forward to releasing a series of Buyer’s Guides covering all-flash arrays in the coming months, it can break these all-flash arrays into five (and soon to be six) general classifications based upon their respective architectures and use cases.
When flash first started to find its way into storage arrays around 2010, these all-flash arrays generally found themselves in two general groupings. On one side, you had existing storage arrays built to hold and manage hard disk drives (HDDs) being re-purposed and filled with solid state drives (SSDs). On the other side, you had emerging and new start-ups that were bringing to market all-flash arrays purpose built to manage and optimize flash.
Unfortunately, neither one really addressed the concerns that enterprises had. Existing storage arrays addressed data management, stability, and reliability concerns, but did not really deliver on the full potential of flash’s performance characteristics. New all-flash arrays purpose-built for flash largely delivered on flash’s potential for performance, but still left question marks in their minds in terms of their stability, reliability, and levels of support.
Those concerns on both ends of the spectrum have largely been put to rest by the current generation of all-flash arrays. While differences between their respective data management, performance, reliability, scalability, and stability on each platform yet remain, the gaps between them are not nearly as wide as they once were. It is as these gaps have closed that five specific all-flash array architectures have emerged that make certain models better positioned to handle certain use cases than others. These five include:

1. Elastic all-flash arrays. This classification of all-flash arrays is best represented by the generation of all-flash arrays that were purpose-built for flash. This includes models such as those from Dell EMC XtremIO, Kaminario, Nimbus Data, and Pure Storage though DCIG would also include models from HPE Nimble and Dell EMC Isilon in this group. The defining characteristic of this group would be their ability to do scale-out, which encompasses the “set-it-and-forget-it” nature of these all-flash array models.
2. Enterprise all-flash arrays. These arrays are best represented by Dell EMC VMAX, HPE 3PAR, Huawei OceanStor, IBM, and NetApp AFF models. These arrays offer both scale-out and scale-up configurations and are well suited to provide the high levels of performance (1+ million IOPS), do consolidation, and handle the mixed workloads found in enterprise environments.
3. General purpose all-flash arrays. This classification of all-flash arrays is best represented by products such as Dell EMC Unity, FUJITSU Storage ETERNUS AF Series, Hitachi Vantara VSP F series, Nexsan Unity, NEC Storage M Series and Western Digital Tegile. These  dual controller storage arrays have updated their controllers to better manage and optimize the performance of flash while bringing forward more mature data management capabilities.
4. High performance all-flash arrays. This is an emerging class of all-flash arrays which are only starting to come to market now from vendors such as E8 Storage and, later this year, from Kaminario. This class of all-flash arrays will redefine “high performance” by offering 10+ million IOPS using NVMe-oF on their front-end interfaces to hosts. While the practicality of implementing these all-flash array solutions is limited in the near term, these arrays provide an early glimpse of what is coming in the not-too-distant future.
5. Utility all-flash arrays. This final grouping of all-flash arrays includes products such as the HPE MSA series, the IBM FlashSystem 900, the NetApp E-series, and SanDisk Infiniflash. These are for organizations who only intend to connect a relatively few number of applications to the all-flash array, need high levels of performance and reliability, and not a whole lot more. Due to the reduced number of data management features on these arrays and their purpose-built nature, they often come at a very attractive price point on a raw per GB basis when compared with the other all-flash arrays mentioned here.

This maturing of the all-flash array market, however, comes with a caveat. It appears another round of maturation will again occur in the next 5-10 years that will create yet a sixth and perhaps final class of all-flash arrays: Composable All-flash Arrays.
This final classification for all-flash arrays may actually serve to be end game for all five of these current all-flash array classifications as software-defined storage takes hold in enterprises and the need for all-flash arrays to manage and deliver both data management and performance decreases. While that day does not appear to be imminent, in light of how quickly enterprises are adopting the cloud architectures and software-defined storage, the adoption and spread of composable all-flash arrays may occur more quickly that many suspect.
Editor’s note: This blog entry was updated on February 5, 2018, for grammar and technical accuracy of the AFAs mentioned.