The Why and How of an All-Flash Enterprise Storage Array

Enterprise storage is an $30 billion a year industry dominated by spinning disks. Flash storage is poised to take a large chunk of the market, having grown significantly in capacity and production, driven by consumer electronics. Flash's technical advantages over disk promise storage arrays that are faster and easier to use while consuming less power and costing less.

The downsides of flash (inc. large erase blocks, limited overwrites, and higher price) mean that using flash as a drop-in replacement for disk leads to increased price, volatile performance, and decreased reliability.

In this talk, we describe the design of the Pure FlashArray, an enterprise storage array built around consumer flash storage. The array and its software, Purity, play to the advantages of flash while minimizing the downsides. Purity writes to flash in multiples of the erase block size and stores its metadata in a key-value store that minimizes overwrites and stores approximate answers, trading extra reads for fewer writes. And, Purity reduces data stored on flash through a range of techniques, including compression, deduplication, and thin provisioning.

The net result is a flash array that deliver a sustained read-write workload of over 100,000 4kb I/O requests per second while maintaining sub-millisecond latency. With many customers seeing 4x or greater data reduction, the Pure FlashArray ends up being cheaper than disk too.