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Western Digital ships enterprise SAS-based 3D NAND SSDs

Tired of waiting for NVMe? Western Digital's HGST Ultrastar-branded 12 Gbps SAS-based 3D NAND SSDs target high-performance virtual, database, analytics and cloud workloads.

Western Digital Corp. is out with its first 3D NAND SAS solid-state drive.

Western Digital this week said its 12 Gbps Ultrastar SS300 is shipping to OEM partners who will sell the drives in enterprise storage arrays and servers. The Ultrastar SS300 comes from Western Digital's HGST division and was developed with partner Intel. The SSD is aimed at virtualized systems, high-performance databases, analytics, video production, and private and hybrid cloud deployments.

The Ultrastar SS300 is Western Digital's highest-performing SAS SSD. The vendor claimed internal tests showed up to 400,000 IOPS for small-block 4 KB random-read workloads and 200,000 IOPS for 4 KB random writes.

Western Digital joined Samsung as the only SSD vendors to ship SAS SSDs based on 3D NAND flash, according to Greg Wong, founder and principal analyst at Forward Insights in North York, Ont. He said 3D NAND enables higher capacity and better performance, especially for writes, over 2D NAND.

Wong noted that Intel, Micron and Samsung currently sell SATA-based 3D NAND SSDs. At 6 Gbps, SATA is a slower drive interface than SAS, although SATA drives often have a cost-per-gigabyte advantage over SAS drives. The 12 Gbps SAS Ultrastar SS300 can negotiate down to 6 Gbps if the host requires the lower speed.

The various flavors

The 2.5-inch HGST Ultrastar SS300 SSD offers users four flash endurance options and a variety of capacity choices:

  • Multi-level cell (MLC) 3D NAND SSDs offering 10 drive writes per day, with capacity options of 400 GB, 800 GB, 1.6 TB and 3.2 TB;
  • MLC 3D NAND SSDs offering three drive writes per day, with capacity options of 400 GB, 800 GB, 1.6 TB and 3.2 TB;
  • Triple-level cell (TLC) 3D NAND SSDs at approximately one drive write per day, with capacity options of 480 TB, 960 TB, 1.92 TB, 3.84 TB and 7.68 TB; and
  • TLC 3D NAND SSDs at about 0.5 drive write per day, with capacity options of 1.92 TB, 3.84 TB and 7.68 TB.

The MLC 3D NAND Ultrastar SS300 SSDs afford greater endurance and higher sequential write throughput and random write IOPS options than the TLC 3D NAND Ultrastar SS300. But both the MLC and TLC options have a maximum sequential throughput of 2,100 MBps for reads at 14 watts of power. The TLC SSDs provide higher capacity limits.

Eddie Ramirez, senior director of enterprise SSD product management at Western Digital, said the company sells HGST- and SanDisk-branded NVMe-based PCI Express (PCIe) SSDs that offer higher performance than the new SAS-based 3D NAND SSDs. The NVMe-based HGST Ultrastar SN200 PCIe SSD, for instance, gets more than 1 million small-block, random-read IOPS, Ramirez noted.

But because less-scalable NVMe-based server and storage architectures are currently limited to 48 SSDs or less, the SAS interface is often the preferred option for enterprise server and storage systems that deploy high numbers of drives, Ramirez said.

"As NVMe infrastructure matures, then potentially the number of drives in a system could scale. But, today, that's why SAS is still an important interface," Ramirez said.

Ramirez said the Ultrastar SS300 SSD offers several endurance options because the company's end customers present different requirements. He said customers that use SAS SSDs as a caching layer behind hard drives often require a high-endurance SSD that can handle lots of writes. All-flash arrays, by contrast, might target read-intensive workloads and be able to use higher-capacity SSDs with a lower endurance level, he said.

Both the MLC and TLC Ultrastar SS300 models offer power options of 9 watts, 11 watts or 14 watts. The new 14-watt option offers the maximum performance for the latest systems, according to Ramirez. He said the 11-watt option targets legacy systems that might need replacement drives for worn-out SSDs. And the 9-watt power budget could hold appeal for customers that want the best total cost of ownership for their SSDs and the most IOPS per watt, he said.

Western Digital said OEMs are qualifying the SS3300 SSDs. Oracle is the only partner to publicly disclose plans to use the drives.

"Each OEM typically will take a three- to four-month qualification timeline to qualify their end system with these drives, and that could vary depending on OEM," Ramirez said. "So, end customers may see them in their systems at different points, depending on which OEM that they're ordering their storage systems from."

All of the Ultrastar SS300 SSDs are guaranteed for five years or a specified maximum number of petabytes of data written -- whichever occurs first. Pricing was not disclosed.

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