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Western Digital subsidiary HGST Inc. has released the second generation of its Ultrastar family of 12 gigabytes per second serial attached SCSI solid-state drives, which use 20 nanometer multi-level cell NAND flash from Intel and offer up to 1.6 terabytes of capacity.
HGST's first-generation of Ultrastar serial attached SCSI (SAS) drives used 25 nanometer (nm) flash and capped out at 800 MB. The second-gen drives also have new controller firmware to reduce latency of individual command lines.
As with the previous generation, the new Ultrastar family includes read-intensive (MR), mainstream (MM) and high endurance (MH) models. Each SSD is rated for 130,000 random read IOPS per second and 1.1 gigabytes per second (GBps) of sequential read throughput, with varying write endurance.
The mainstream Ultrastar SSD1600MM, designed for use with high-end storage systems and database servers, provides write endurance up to 10 drive writes per day (DWPD) for five years and 70,000 write IOPS. It is available in capacities of 200 MB, 400 MB, 800 MB and 1.6 terabytes (TB).
The Ultrastar SSD1600MR is designed for read-intensive applications such as data analytics, with 30,000 write IOPS. It is rated for up to 2 DWPD for five years. Its capacity options are 250 MB, 400 MB, 500 MB, 800 MB, 1 TB and 1.6 TB.
The Ultrastar SSD800MH.B provides the highest write endurance and lowest capacity. Targeted primarily at tiered storage systems that need write caching, it is available in 100 MB, 200 MB, 400 MB and 800 MB capacities, and is rated for 25 DWPD for five years and 110,000 write IOPS.
"HGST has made a concerted effort to design an SSD architecture and controller that efficiently manages the NAND flash and delivers a high level of data integrity, as well as provide a number of security options that deliver the enterprise-class performance and endurance required," said Jeffrey Janukowicz, research director at IDC.
"The wide array of capacity points and different endurances enables storage system manufacturers and end users "to optimize for a given application or system with the right drive to fit the workload," Janukowicz said.
HGST unveiled 12 GBps Ultrastar drives in 2013 with 25 nm NAND flash. To accommodate the move to 20 nm NAND memory, the company redesigned its controller firmware to improve error correction and NAND management capabilities, particularly narrowing the distribution of underlying commands.
The firmware is optimized to ensure back-end processes of wear leveling, disk defragmentation and duplication avoidance don't interfere with commands coming from host machines.
"While it doesn't show up in a typical data sheet, we believe this can improve the performance of our product by a factor of 2X to 3X," said Ulrich Hansen, HGST's vice president of marketing for SSDs.
HGST and Intel formed a partnership for SAS controllers in 2008. HGST continues to rely on the Intel NAND flash, even after acquiring several of its own flash companies, including SSD vendor sTec Inc., in 2013.
"The MLC (multi-level cell) NAND flash and the controller we've developed with Intel allows us to reach high endurance capabilities in a cost-effective design point," Hansen said.
As process geometries shrink and NAND becomes more affordable, the technology is expected to show up in more enterprise deployments. IDC forecasts shipments of SAS SSDs to increase by nearly 50% by 2018.
HGST, formerly Hitachi Global Storage Technologies, was acquired by Western Digital for $4.3 billion in 2011. HGST's enterprise SSD business contributed $395 million in revenue to Western Digital's balance sheet through the first three quarters of 2014. That's on the heels of a 446% revenue jump ($65 million to $355 million) between fiscal years 2012 and 2013.
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