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Shannon Systems Direct-IO G3i 6.4TB Enterprise SSD Review

Shannon Systems Direct-IO G3i 6.4TB Enterprise SSD Review

The Shannon Systems Direct-IO G3i series comes in capacities of 800GB, 1.2, 1.6, 3.2 and 6.4TB and offers up to 590,000/480,000 4K random read/write IOPS and 2.6/1.6 GB/s of sequential throughput.

The Shanghai-based Shannon Systems was founded in 2011 with a core group of engineers with over 60 years of experience in the flash industry and over 150 patents. The company utilized its experience to develop the Direct-IO series of PCIe SSDs, which incorporate proprietary IP and drivers that bypass the traditional storage protocols, such as SCSI and AHCI, and instead interfaces directly with the NAND media (much like a CPU interacts with DRAM).

Shannon Systems has an established customer base in China that includes some of the superstars of web-scale architectures, such as China Mobile, China Telecom and Alibaba. The Chinese hyperscale market consists almost entirely of greenfield data centers, and without the legacy baggage of existing infrastructure its data centers are cutting edge and flash-powered. In fact, China is one of the largest and fastest growing SSD markets. The Chinese government has placed intensifying restrictions on foreign products, so the natively produced Direct-IO products already have a leg up on the foreign competition.

The company has a strong beachhead in Chinese data centers, but also has its eyes on the global market. The biggest step forward on that front came in the form of Shannon Systems' acquisition by SMI (Silicon Motion Technology Corporation) for $57.5 million in July 2015. SMI produces SSD controllers and has a significant presence in the global market.

Four of the top five NAND fabs, among many others, utilize SMI controllers and the combination of the IP from both companies and the global sales channel is a win for both sides. In fact, SMI reported that in its recent quarter sales of Shannon enterprise-grade PCIe SSDs nearly doubled. This is impressive in light of Shannon's 2013 revenue of more than $1 billion.


The Shannon Systems Direct-IO G3i series comes in capacities of 800GB and 1.2TB in the HHHL form factor, and 1.6, 3.2 and 6.4TB in the FHHL form factor. The 3.2TB and 6.4TB models offer up to 590,000/480,000 4K random read/write IOPS and 2.6/1.6 GB/s of sequential read/write throughput. The Direct-IO G3i series features several form factors, including hot-pluggable 2.5" U.2 models with up to 2.4TB of capacity. The SSDs all support either ONFI or Toggle NAND in both 2D and 3D flavors and feature 5 DWPD of endurance (three-year warranty period). Our 6.4TB sample employs Toshiba A19nm flash, but some of Shannon's customers are utilizing Micron flash products.

The Direct-IO SSDs feature a PCIe 2.0 x8 Kintex FPGA in lieu of the more-traditional ASIC found on many PCIe SSDs. The proprietary drivers allow Shannon to forgo the use of DRAM and onboard I/O processing—it instead utilizes the host DRAM and CPU for management of internal SSD features, such as garbage collection, error detection and correction, wear leveling and static data rotation, among others. This approach is in contrast to the onboard processing and DRAM employed with the majority of NVMe SSDs. A few vendors still employ proprietary driver stacks, such as HGST with its Virident-based products and SanDisk with its ioMemory products.

Offloading compute and DRAM resources (which manage the LBA tables) to the host has advantages. It reduces the number of onboard components, which reduces power consumption, possible failure points, design and firmware complexity and increases density. The 6.4TB Direct-IO model manages to stay under the 25W power consumption envelope, which is impressive in light of its incredible capacity, but largely due to the elimination of power-hungry onboard DRAM. We take a closer look at the architecture on the following page.

Shannon Systems also has its Direct-IO G3S series and a PCIe-RAID architecture that allows administrators to aggregate the performance of numerous SSDs into one pool and infuses them with HA characteristics.

The overall Direct-IO architecture is geared to offer a high-capacity yet value-centric alternative to standard offloaded architectures. Not all applications require eye-watering performance specifications on the upper-end of the performance spectrum, so a tradeoff of incrementally lower performance under heavy load for lower cost and higher capacity is more than acceptable, and also results in the best application performance.

Shannon Systems is setting out to capture a slice of the global PCIe SSD market, and with SMI's global experience, the future is bright. However, the SSD market is brutally competitive, no matter the location. Let's see how the Shannon Systems Direct-IO G3i fares against the competition and if it provides a compelling mix of cost-v-performance.   

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