Update. Read/write bandwidth and latency numbers added. 25 June 2020.
WD has built a faster NVMe SSD and populated an OpenFlex NVMe-oF composable JBOF enclosure with 24 of them to provide a hot box, fast-access data centre flash array.
This is somewhat surprising as WD has recently divested its data centre storage array business, witness the disposal of IntelliFlash arrays to DDN and ActiveScale archiving to Quantum. But the OpenFlex box does not have a storage controller delivering data services: it’s bare metal.
A canned quote about the new WD products from IDC research VP Jeff Janukowicz struggled to say anything specific about them: “The future of Flash is undoubtedly NVMe as it’s all about speed, efficiency, capacity and cost-effective scalability, and NVMe-oF takes it to the next level. … the company is well positioned to help customers fully embrace NVMe and get the most out of their storage assets.”
Yusuf Jamal, SVP of WD’s Devices and Platforms Business, provided an anodyne quote, too: “We’re fully committed to helping companies transition to NVMe and move to new composable architectures that can maximise the value of their data storage resources.”
The SSD
The DC (Data Centre) SN840 uses the same 96-layer 3D NAND TLC technology as the earlier SN640 and its capacity range is 1.6, 3.2, 6.4 (3 drive write per day) or 1.92, 3.84, 7.68, and 15.36TB (1DWPD) in its U.2 (2.5-inch) form factor. The 15.36TB peak is double the earlier SN640’s 7.68TB in its U.2 form factor. That drive also came in a 30.72TB EDSFF E1.L ruler form factory, which format is not available for the SN840.
The SN840 outputs up to 780,000/250,000 random read/write IOPS, much more than the SN640’s maximum 480,000/220,000 IOPS. The sequential read/write bandwidth numbers are 3.5GB/sec and 3.4GB/sec, and the latency is 157µs or lower.
Its 1 and 3 drive write per day formats make it suitable for either read-intensive or mixed read/write-use workloads. The SN840 is a dual-ported drive with power-loss protection and TCG encryption.
The JBOF
The OpenFlex Data24 NVMe-oF Storage Platform is a 2U x 24 slot all-flash box populated with the SN840 SSDs. It uses an RDMA-enabled RapidFlex controller/network interface cards, developed with WD’s acquired Kazan Networks NVMe-oF Ethernet technology. Notice the vertical integration here.
This JBOF (Just a Bunch of Flash) follows on from the OpenFlex F3100 which was an awkward design housing 10 x 2.5-inch SSDs inside 3.5-inch carriers.
The 2U Data24 box houses 24 hot-swap SN840s with a maximum 368TB capacity. Up to 6 hosts can be directly connected to this JBOF with a 100GbitE link and 6 RapidFlex NICs. They get the benefit of up to 13 million IOPS, 70GB/sec throughput and sub-500 nanosecond latency.
The Data24 can interoperate with the existing OpenFlex F-series products and comes with a five-year limited warranty.
It’s certainly a fast box and comes with no traditional storage controller providing data services such as erasure-coding, RAID, snapshots, or data reduction. This is just a stripped down, NVMe-oF-accessed bare flash drive dragster box supporting composability.
WD said it can be used for high-performance computing (HPC), cloud computing, SQL/NoSQL databases, virtualisation (VMs/containers), AI/ML and data analytics. We envisage DIY hyperscalers and system builders will be interested in looking at the box, as a SAS JBOF replacement perhaps. All WD’s data centre SSD customers will pay attention to the DC SN840.
Ultrastar DC SN840 NVMe SSD shipments will begin in July. The OpenFlex Data24 NVMe-oF Storage Platform is scheduled to ship in autumn/fall. RapidFlex NVMe-oF controllers are available now.
