12G SAS: Just What the SSD Ordered

The new generation of SAS technology promises to turn SAS from a simple drive interface into a fully functional storage fabric.

By Arthur Cole | Posted Jun 21, 2013
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Solid state drives (SSDs) provide faster storage performance than their HD brethren. But that performance means nothing to the wider data environment if the surrounding network infrastructure runs too slow to accommodate it.

Enter the next generation of SAS technology: a 12Gbps interface that essentially doubles performance over existing 6G solutions and provides a number of additional tweaks, like improved electrical signaling and advanced power and cable management, which promise to further SAS’s transition from a simple drive interface to a fully functional storage fabric.

Most importantly, however, 12G SAS enables a maximum 48Gbps through a standard 4-lane architecture, enabling full saturation of the PCIe 3.0 bus for significantly higher densities in storage network infrastructure, which should go a long way toward reducing complexity and lowering operating costs and energy consumption.

At the moment, the market is in a state of flux. Most of the leading drive manufacturers are ready to push products into the channel even though there are no RAID adapters or HBAs available, save for a few OEM models and limited-issues to systems integrators. But if the drives themselves are any indication, SSD storage infrastructure is about to push enterprise environments to entirely new levels of performance.

Toshiba seems to be the first to hit the channel with an actual product, the PX02SMx series, which the company is targeting at Tier 0 applications (natch). The device is the company’s first to feature 24 nm eMLC NAND technology and is outfitted with a dual-port interface and support for both AES 256-bit encryption and advanced cryptographic erase technology. Capacities range from 200GB up to 1.6TB, with write endurance rated at 29.2 PB over an estimated five-year lifespan, which works out to about 10 writes per day.

This followed Seagate’s announcement last month that it would introduce a 12G drive as part of a comprehensive flash memory portfolio. The Seagate 1200 is backed by a set of proprietary algorithms that the company says optimize the drive for frequently accessed data by prioritizing storage functions like reads and writes as well as the physical location of data on the drive itself. Capacity scales up to 800GB on either a 1.8- or 2.5-inch form factor, and the device is outfitted with data integrity features that protect against power loss and corruption.

Western Digital is also scheduled to join the party in the next month or so with the planned release of the newest Ultrastar models – the SSD800MH, the SSD800MM and the SSD1000MR – aimed at high-frequency trading and online transactional applications. The drives will initially range from 200GB to 1TB, although the company is said to be prepping 2TB and 3TB versions as well. The company boasts 25 full drive writes per day over five years for the 800MH model, and a 0.44 percent failure rate across the entire line, or about 2 million MTBF.

Of course, how awesome would it be to gain 12Gbps performance over 6Gbps infrastructure? That’s what LSI is offering with its DataBolt bandwidth optimization system, which employs a range of techniques to double current SAS connectivity. Through bandwidth aggregation, intelligent buffering, and SAS/SATA bridge technology, the company says it can deliver full compatibility with the 12Gbps SAS T10 spec using either 6G or 3G SAS endpoints.

As the old saying goes, networking is only as strong as its weakest link. In storage environments, drive interface speeds were traditionally developed in conjunction with the drives themselves: spinning platters could only access data so fast, so it didn’t matter that the interface was slower than most of the networking and processing technology around it.

But there’s a new storage sheriff in town, and his initials are SSD. With throughput and access happening at lightning speed within the drive now, it is high time the interface stepped up its game as well.

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