August 20, 2012

A Petabyte of Flash in a Rack

Michael Feldman

Solid state storage specialist Nimbus Data Systems has unveiled its third-generation flash memory array, setting new benchmarks on resiliency, performance, and capacity. The new product, known as Gemini, offers up to 48 TB of capacity and over 1 million IOPS per 2U box. And despite moving to the less expensive and less reliable consumer-grade MLC flash, Nimbus has managed to double the endurance of its storage arrays.

Nimbus main market strategy has been to offer all-flash storage systems that compete on a cost-capacity with 15K spinning disk systems, but at much higher performance, density, and energy efficiency. The Gemini offering promise to do even better on all three counts thanks to this technology upgrade. It will also shave off a couple of dollars per gigabyte in up-front cost — $8/GB for Gemini versus $10/GB for Nimbus’ second-generation S-class arrays, which were based on the more expensive enterprise MLC flash (eMLC). At that price, it’s harder than ever not to seriously start looking at flash for primary storage.

Not that Nimbus buyers needed much encouragement. According to company CEO and founder Thomas Isakovich, Nimbus has already collected 230 customers, including big accounts at eBay, the US Department of Defense, and major wins at the world’s largest news provider and largest content provider. On the heels of 10 consecutive quarters of profit growth, year-over-year revenue grew 500 percent. If Gemini lives up to its specs, Nimbus has a good chance to continue that breakneck pace.

Just on a capacity basis, the new 2U box more than quadruples the maximum storage, from 10 TB in the previous S-class product to 48 TB for Gemini. That works out to about a petabyte per rack, which is 8 times denser than what a typical 15K disk storage system can achieve.

Impressive as that is, it’s still not as dense as the enterprise MLC flash systems unveiled last week by Skyera, another Silicon Valley startup looking to cash in on enterprise flash storage. Skyera’s new Skyhawk box puts 44 TB in a 1U box, nearly twice the density of Gemini. And like Gemini, each Skyhawk box promises up to a million IOPS.

Unlike Skyera however, which currently offers an Ethernet-based SAN solution, Nimbus supports both SAN and NAS protocols, as well as all the standard network flavors — Ethernet, Fibre Channel and InfiniBand (now including FDR). The Gemini software also allows users to switch network protocols on the fly, offering the ultimate in flexibility. In addition, Nimbus will warranty their new MLC-based gear for a full 10 years, twice as long as Skyera’s 5-year guarantee.

But according to Isakovich, the most notable new capability Gemini adds is nonstop availability. Each 2U box now comes with two flash storage controllers for complete redundancy (Gemini twins, get it?). The controller itself, also known as Gemini, is Nimbus’ first completely custom board. It’s designed to eliminate any single point of failure as well as enable maintenance like software update, capacity expansion, and component hot swaps (storage processors, drives, power/fans) to take place without powering down the system.

Gemini also incorporates what the company calls “Flash Lifecycle Management,” which provides the essential functions of error correction and wear leveling in order to cope with the more severe endurance problems that consumer-grade MLC brings with it. Specifically, they’ve taken wear leveling to the extreme. Not only does the controller spread write operations across all the flash drives in the box, but also across the flash chips themselves. According to Isakovich, that makes it possible to write as much as 1.2 petabytes per week for up to 10 years.

Underneath the covers of Flash Lifecycle Management is something called “Distributed Cache Architecture,” a patent-pending technology in which the cache is located on the flash drive itself rather than upstream at the controller. In the Nimbus design, the cache is located on a DRAM chip that Nimbus has glued to the drive and is controlled by an on-board ASIC (which is also doing ECC and wear leveling). This setup has a number of advantages including eliminating the need for mirroring in a multi-controller configuration and allowing cache to scale automatically as flash capacity grows.

“At the end of the day, the customer only vaguely cares about any of this,” says Isakovich. “All they want to know is: ‘If the flash burns out, are you going to stand by it?’ And our answer is: absolutely.”

Even though Nimbus’ mainstream customers are running enterprise workloads — server virtualization, databases, virtual desktop infrastructure, and big data-type apps — high performance computing is another market the company has found some traction. According to Isakovich, the company has some wins at supercomputer centers, although none of these customers have gone public yet. Some of these HPC buyers deployed with the older S-class systems, but others apparently held out for Gemini.

Certainly a petabyte storage rack delivering 20 million IOPS, hooked directly to a supercomputer’s InfiniBand network, would be a tempting setup for a range of data-intensive applications. That kind of solid state capacity is not going to come cheap though. Even at $8 per gigabyte, a full petabyte would run a cool $8 million. Nimbus, of course, would love to sell such a system.

The new Gemini gear will be available in the fourth quarter of 2012.



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