The company said the system, called ExtremeFFS and announced at the WinHEC 2008 trade show in Los Angeles, will ship in SanDisk products next year.

Decoupling Physical and Logical Locations

Rich Heye, senior vice president and general manager for SanDisk's SSD Business Unit, said SSDs used with Windows Vista require a large number of random writes instead of sequential access.

To get the best performance out of such random writes, SanDisk created ExtremeFFS. The company said the system operates on a page-based algorithm, which means physical and logical locations can be separated. The SSD can write data to wherever is most convenient and efficient, which results in a performance improvement of as much as 100 times.

ExtremeFFS also uses all the NAND (not and) channels independently, so some can write while others deal with what the company called "garbage collecting." The system can also learn user patterns because it has usage-based content localization. After many uses, it knows where to place data for better performance and endurance. "This feature might not show up in benchmarks," Heye said, "but we believe it is the right thing to do for end users."

New Metrics

Because of the new ways that ExtremeFFS tackles the performance issue, SanDisk has suggested that new metrics are needed to measure the improvement, especially in comparing SSDs with hard disk drives.

Heye said that, since hard-drive performance is measured in revolutions per minute, or RPMs, SSDs need a comparable metric, such as virtual RPM or vRPM. He added that vRPM answers the question, "How fast would you have to spin a virtual HDD to achieve the level of performance seen by an SSD in a client PC?"

With this metric, Heye predicted, the net performance of a SanDisk SSD in 2009 could be four times faster than the current generation and almost six times faster than the latest 2.5-inch hard disk drives.

SanDisk is also proposing the first industry measurement of Long-Term Data Endurance (LDE). The metric has been submitted by SanDisk to JEDEC, which develops standards for the solid-state industry.

Heye said LDE is "like measuring tread wear on a tire." The metric measures the total amount of data writes that occur during the lifespan of a SSD. Even before it is approved as an industry standard, SanDisk said it will include LDE on future products.

Based in Silicon Valley, SanDisk describes itself as "the inventor and world's largest supplier of flash storage cards." Its portfolio of products includes flash memory cards for mobile devices, digital audio/video players, SSDs for computers, and USB flash drives for consumer and business markets.