Seagate is refreshing its entire line of enterprise SSDs, and it continues the trend by kicking density up a notch with the demonstration of a prototype 60 TB SSD at the Flash Memory Summit. Seagate indicated that the SSD is a technology demo, but the company based the overall design of the new SSD on proven and mature technology. A more refined version of the SSD will eventually come to market.
The 60 TB SSD comes in the 3.5″ form factor, which is much larger than the standard 2.5″ designs that we are accustomed to. Early enterprise SSDs came in the 2.5″ form factor but eventually transitioned to 2.5″ as flash continued to shrink, thus allowing SSD vendors to cram more capacity into smaller SSDs. The shrinking trend continues today as m.2 SSDs become more plentiful. Seagate is betting that the incredible density of the 3.5″ SSD, which can enable up to 1PB of storage with only 17 SSDs, will be a hit for system builders.
Samsung debuted its 16TB PM1633 last year in a 2.5″ form factor, but the increased real estate of the 3.5″ form factor and several architectural advancements allows Seagate to offer more density than two PM1633a units combined. The Seagate SSD uses 3D TLC NAND to reach the heights of storage capacity, but the company tied the SSD to a 12 Gbps SAS interface. Many of the fastest SSDs on the market employ the PCIe connection in tandem with the NVMe interface, but Seagate geared the new SSD for read-intensive workloads, large storage arrays and active archive use cases, which means the SSD focuses on cheap capacity instead of high performance. Twelve Gbps SAS also provides a dual-port capability, which allows two servers to access the SSD to provide HA (High Availability) functionality. Some SAS SSDs also employ a wideport scheme to access both ports in tandem to provide more performance.
| Seagate 60 TB 12 Gbps SSD | |
|---|---|
| Capacity (TB) | 60 |
| Form Factor | SFF 3.5″ |
| Interface / Architecture | Dual 12 Gbps SAS |
| Sequential Read (MB/s) 128KB | 1,500 |
| Sequential Write (MB/s) 128KB | 1,000 |
| Random Read (IOPS) Sustained 4KB QD32 | 150,000 |
| Power: Active Max Average (W) | 15 |
A co-branded LSI/Seagate TT50761 controller works in concert with an array of eASIC ONFI bridges, which allows the SSD to employ scalable channel interleaving. This technique allows the SSD to address up to 1,280 flash die per controller. The ONFI bridge arrangement allows Seagate to carve out varying capacities by simply adjusting the number of bridges and NAND packages.
The performance specifications are somewhat conservative at this point, which is likely due to tying such a large amount of flash to a single SSD controller. Seagate noted that it does not plan to ship the SSD this year, at least not in its current form, but that a variation of this will likely come to market in 2017.
