Fusion-io (proprietary)

Fusion-io's storage architecture is fundamentally different from conventional SSD controllers. Rather than presenting a SATA or SAS block device, the ioDrive family consists of PCIe 2.0 x4 add-in cards that attach NAND flash directly to the PCIe bus, eliminating the SATA/SAS stack entirely. The interface to the host OS is provided by Fusion-io's proprietary VSL (Virtual Storage Layer) driver, which exposes the storage as a low-latency block or raw flash device depending on configuration.

The ioDrive cards use a custom Fusion-io ASIC whose internal specifications were not publicly disclosed. Performance was exceptional for the era: the single-module ioDrive delivered sequential reads around 770 MB/s and over 100,000 random read IOPS, figures that consumer SATA SSDs would not approach for several years. The ioDrive Duo doubled capacity and throughput by mounting two modules on a single card. Fusion-io cards were adopted at scale by Apple, Facebook, and other hyperscalers before NVMe standardized the PCIe flash interface. Fusion-io was acquired by SanDisk in 2014.