A recent analyst report makes the following claim
“Solid-state arrays have reached a level of maturity, reliability and cost-effectiveness that they now exceed hybrid disk arrays in all characteristics except raw capacity, providing I&O leaders with agility and service improvements.”
Most solid-state arrays are architected as midrange systems which lack enterprise capabilities, like virtualisation of external storage, remote replication, and active/active controllers. An Industry analyst chooses to define Solid State Arrays as “All Flash Arrays” (AFA) which means that they cannot attach hard disks either directly or through virtualization and must have a separate product number. They fail to recognize that a hybrid disk array like the enterprise Hitachi VSP G series can do everything and more that an “AFA” can do. The VSP G series can contain just flash modules if the customer decides to use it as an all flash array but it does not qualify as an AFA according to this definition. Customers who follow this definition often do not consider the VSP G series as an AFA. For this reason, we have created the VSP F Series which can only attach Hitachi Flash Modules (FMD). The F series cannot virtualize external storage arrays.
The logic behind the AFA definition has been questioned by other industry analysts like Howard Marks, but it is what it is.
As far as the analyst statement goes, our VSP F series AFA has the same level of maturity and reliability of our hybrid VSP G series since they have the same basic architecture. However, since the F series is restricted from virtualizing external storage, this restricts its ability to match the G series in cost effectiveness and raw capacity. Other AFA vendors cannot match either the VSP G or F series in enterprise scalability, availability, and functionality and many cannot match the raw performance. Both the G and F series offer the industries only 100% availability guarantee.
Why is virtualization of external storage arrays so important? In that same report the analyst says:
“By 2020, the percentage of data centers that will use only SSAs for primary data, instead of hybrid arrays, will increase from less than 1% in 2015 to 25%”. That means there will still be a lot of disk storage systems around that could gain the performance and operational benefits of flash storage if they were virtualized behind a front-end hybrid flash system like the VSP G series.
Most of our customers still choose the hybrid VSP G series over the F series due to the flexibility that the hybrid approach provides in implementing flash. An example today is the current supply constraints around SSD’s brought about by NAND technology transitions, factory yields, and competing memory demands by smart phones and PCs. Hybrid storage array customers can fill their storage demand needs with available disk storage as a tier behind their existing flash.
The future is certainly all flash, but during the transition, a hybrid storage system, can help by providing the benefits of flash through virtualization before the before the disk systems are fully displaced. In the future, when new technology replaces NAND flash, a hybrid storage system will again help in the transition as it does today.