Figuring the TCO for Solid-State Disks

How quickly and to what extent businesses and other enterprises embrace solid-state technology in their storage infrastructure is an issue of heated debate among industry analysts and SSD vendors. In the end, it will probably boil down to the mundane calculation of total cost of ownership, which includes a variety of factors such as the benefits derived from an increase in performance.

The interesting thing about TCO is that while it is methodical, it is never uniform. Every enterprise has its own approach to calculating TCO, and then factoring TCO into equipment evaluations and buy decisions. However, nearly all enterprises consider price points, efficiency, performance, quality, and reliability in their TCO assessments.

The significance of Sun Microsystems Inc. (Nasdaq: JAVA) and Micron Technology Inc. (Nasdaq: MU)s December announcement, of highly durable NAND flash memory with single-level cell (SLC) write cycles that have increased from 100,000 to 1 million cycles and multi-level cell (MLC) write cycles that have gone from 10,000 to 100,000 write cycles, chips away at the reliability questions about NAND in TCO assessments. It also more closely matches NAND with enterprise expectations of durability. The advances in write-cycle performance are intended to overturn enterprise perceptions that question both NAND's reliability and durability -- and to let enterprise decision makers know that NAND is ready for enterprise applications.

"We are working with several enterprise vendors and are developing a new class of NAND for enterprises," says Michael Cornwell, lead technologist of flash memory at Sun Microsystems. "Traditional NAND flash was designed for consumer applications, but we have worked with others within the industry on the specific demands of enterprise users and feel we now have a product that can meet the needs of the 24x7 enterprise."

Of course, it is going to take more than reliability and durability to win in enterprise TCO assessments."When we looked at NAND strategically, we felt that enterprise concerns about reliability were the first things to tackle, so improving NAND write cycles dramatically for durability has gone far to resolve that," Cornwell says. "The next phase is to develop high-speed interfaces to NAND flash that can keep up with a NAND memory array capable of speeds of 700 to 800 megabits per second -- and not bottleneck it with interface speeds of 40 megabits per second."

Samsung Corp. also sees the necessity of working on hardware interfaces for gains in performance. It recently unveiled a 100GB enterprise SSD that is 10 times faster than the fastest 15,000 rpm SAS HDD. The new SSD customizes the controller with firmware and uses more channels to speed performance. "This product has the capacity to yield high IOPS [input/output per second], while using significantly less power than hard drives," says Steve Weinger, Samsung senior marketing manager. "Enterprises are pursuing green initiatives, and meanwhile they are running out of power, emitting carbon dioxide and running out of space. Alternatively, SSDs can operate in a normal environment without the need for cooling, and they can dramatically reduce the footprints of storage in the data center."

To be sure, data center green initiatives that bring in energy savings are important to many enterprises, and they factor well into enterprise TCO formulas. Equally as important is getting enterprise decision makers comfortable with NAND and SSD technology that can bring improved performance to existing applications.

"When we consider potential enterprise applications for NAND, we look at memory in a kind of hierarchy, with low-cost applications like archiving at the base of the pyramid, and high-cost, processing-intensive applications at the top of the pyramid," says Kevin Kilbuck, director of NAND market development for Micron. "NAND plays in both of these areas."

One of the most exciting developments has been the emergence of a viable MLC for enterprises. The Sun-Micron work has increased MLC write cycles by a factor of 10, and another collaboration between Micron and Violin Memory Inc. is working to extend MLC life spans so they are at a par with SLC."The benefit of MLC to the enterprise is its lower price point when compared to SLC," says Violin Memory CEO Donpaul Stephens. "MLC is an option for less intensive systems like data archiving, which has traditionally been the province of hard drives." MLC technology in the lower-performance tier of the performance pyramid broadens the application base for enterprise IT to consider NAND and SSD solutions.

The task for most NAND and SSD suppliers continues to be "commoditizing" these products so that IT decision makers not only feel comfortable with the technology, but also with the prices. Today, the best way to approach the price point challenge is via TCO, which extrapolates costs far beyond item-entry ticket prices into longer-term cost-benefit yield areas like power consumption, performance, and the need to invest in less hardware and data center real estate. NAND and SSD are good at this.

"We are one of a number of vendors working to commoditize the market for NAND and SSD so that price is not as great an issue for IT decision makers," says Sun's Cornwell. "To do this, we are focusing on cost-effective solutions that give enterprises competitive price points when they consider their total cost of ownership... We know that every enterprise has its own method for figuring a total cost of ownership. But one thing SSDs can do is to provide greater processing efficiency without waiting for disk I/O, and they can do it with less hardware, which is very compelling."