SSDs move into a class of their own
Start-ups aim to integrate SSDs into new memory hierarchy for enterprise servers.
By Tam Harbert, Contributing Editor -- EDN, August 11, 2009
A new market for SSDs (solid-state disks) is heating up, driven by the needs of high-end servers in data centers.
The I/O bottleneck has gotten a choke hold on enterprise class servers. Particularly within large companies with huge data centers that handle high volumes of data requests – think Google and Twitter – the time it takes for data to move from memory to the processor has become too long. And as software-as-a-service and cloud applications become more popular, it’s only going to get worse.
SSDs dramatically increase the speed at which data moves to the processor. Rather than the milliseconds or seconds it can take to get the data off the hard drive and transfer it to DRAM, SSDs can do it in microseconds, according to Alan Niebel, CEO of Web-Feet Research Inc. Some companies, such as STEC and Fusion-io, have sold SSDs into the enterprise server market for years, but these systems were custom and expensive. Server and storage vendors such as Sun Microsystems and EMC Corp have offered SSDs as options in high-end systems.
Now, as the price of flash has dropped below the price of DRAM, SSDs are moving into the enterprise server mainstream. “We are getting to the point where we are changing the memory hierarchy of these systems,” said Jim McGregor, chief technology strategist at In-Stat. Within the next two years, “you’re going to see companies that serve large enterprise-class customers moving [SSDs] into their standard product lines.”
In mid-July, STEC announced that one of its largest enterprise storage customers signed up for $120 million worth of its ZeusIOPS SSDs for the second half of 2009, doubling the revenue that STEC expects to make from that product this year. The company said the agreement “reflects the enterprise storage manufacturer’s continued commitment to integrate STEC’s SSD technology into the manufacturer’s systems.”
In addition, several start-ups have emerge with something they call “storage-class memory” that is integrating SSD technology into enterprise servers. More than just using SSDs, these companies are modifying the software and redesigning interface controllers to improve speed and overcome some of the weaknesses of flash, such as write endurance.
Three-year-old Virident Systems, for example, is “looking from application requirements down, rather than looking from components up,” said Vijay Karamcheti, chief technology officer. Rather than start with SSDs and figure out how to use them to solve the I/O bottleneck, it aimed to define a better memory system for enterprise servers in large-scale data centers.
In particular, the company looked at database and caching applications. Databases deal with blocks of data, and this data has to be always available or “persistent,” as Karamcheti put it. Both SSDs and hard drives offer block access, persistence and high capacity. On the other hand, they lack the random access available in DRAM. When a database needs a piece of information smaller than a block, the server needs to load a block of information into the DRAM, where it can be accessed. But DRAM isn’t persistent – it is volatile memory that loses its contents when the power is off.
“Storage-class memory gives you the best of both worlds, DRAM-like random access ... and the capacity and persistence of a disk,” said Karamcheti. The company claims that its database server offers 50-times the performance of a traditional industry-standard server and nearly 10-times the performance of best-of-breed SSD-based servers.
The product is an appliance that bundles optimized hardware, optimized operating system software and optimized application software. Virident is targeting the largest growth areas of Web 2.0 infrastructure, such as database and caching applications.
But the technology also holds appeal for more than just the Web 2.0 leviathans. Start-up Schooner Information Technology is packaging IBM System X servers with SSDs, DRAM and specialized middleware to offer similarly integrated appliances for database and caching.
Simply adding SSDs to servers may speed up memory some, but not enough, said John Busch, co-founder, president, and CEO of Schooner. SSDs may produce a 20% improvement, he said, whereas Schooner claims its integrated approach achieves eight- to 10-times the throughput. “We tightly integrate multicore processors, low-latency interconnect, flash memory, and middleware applications into a single building block. We think this is a fundamental trend in the industry.”
Busch said Schooner’s market is mid-sized Web 2.0 and cloud computing companies. “Our first products are targeting Web 2.0 and cloud computing data centers that are building on LAMP,” referring to an acronym to that stands for an amalgam of open-source software used to define a Web server infrastructure.
Integrated approaches like Virident’s and Schooner’s not only speed up performance, but can also dramatically reduce energy consumption, equipment footprint and total cost of ownership, all big selling points for data centers.
Jim Handy, analyst at Objective Analysis, said enterprise servers have become the single biggest market for SSDs in terms of revenue, amounting to just short of $500 million. He forecast last year that it would grow to more than $1.3 billion by 2012, and now estimates that figure should be higher. By the middle of next year, he expects all data centers to be employing SSDs or flash memory in some form or another.
Today, flash’s improving performance and falling price points are driving the technology into new markets. But both NAND and NOR are limited in terms of how small the technology can be shrunk.
“Everybody knows that flash memory is going to hit a wall at some point in the not-to-distant future,” said Handy.
Long-term, the industry will need a new semiconductor memory, Web-Feet Research's Niebel agreed. That means that SSD vendors and semiconductor memory companies are starting to look for a technology to replace flash. Among the possible replacements are phase change memory, resistivity RAM for NOR flash, and CMOx to replace NAND flash.
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SSDs have a more predictable life cycle, enabling pro-active management of storage, unlike rotating media which necessarily follows the 'fix after it breaks' model.
While SSDs may or may not be longer-lived than rotating media, they surely can predict their own remaining lifespan based on the firmware-kept per-block stats on erase events.
Przemek Klosowski - 2009-28-8 22:06:00 PDT
