All-Flash Storage Arrays (AFAs)

For years, the world relied on hard disk drives (HDDs) to store digital information. These electro-magnetic devices worked well and their costs per gigabyte continually decreased. However, they had inherent performance constraints because of the time they required to read or write data on spinning metal platters with magnetic coatings. Burgeoning data troves and new generations of sophisticated applications rendered their read/write times, even when measured in milliseconds, a computing and business bottleneck.


New chip-based technologies emerged that resulted in solid-state drives (SSDs) without any moving parts. They’re much faster than HDDs and provide more predictable response times for time-critical applications, but their costs were high and their storage capacities limited relative to HDDs. They were cost effective in hybrid storage arrays. In these solutions, SSDs cached active data on tier 0 while HDDs still bore the brunt of the storage load.

The costs of SSDs are inexorably decreasing while their capacities increase. Fifteen terabyte SSDs are available and larger sizes are on the horizon. SSDs are beginning to be practical for longer-term storage and for applications that are less speed-critical. As a result, what has emerged is a new storage paradigm known as the all-flash storage array.

Initially, AFAs were too costly for all but enterprise usage, but this is changing. Moreover, AFAs are beginning to leverage the performance of their SSDs. Hybrid arrays generally rely on the same protocols that were developed for HDDs, such as SCSI, SATA, and Fibre Channel. These are incapable of supporting the blistering speeds of SSDs. The industry responded with non-volatile memory express (NVMe), a faster, more efficient protocol developed specifically for flash drives. Moreover, storage system software is becoming multi-threaded so CPU cores can cost-effectively keep pace with flash speeds.

Are AFAs finally practical for small- and medium-sized organizations? They’re still pricey compared to traditional HDD arrays, especially those that are designed for capacity. Yet you must consider more than acquisitions costs. In our next blog, we’ll touch upon some of the considerations and use cases to determine if AFAs make sense for you.