Samsung defends flash reliability in solid-state drives

Samsung is touting the reliability of solid-state drives, while citing an explosive market for the devices in server computers.

SSDs are based on flash memory chip technology and have no moving parts. Hard-disk drives (HDDs), in contrast, use read-write heads that hover over spinning platters to access and record data. With no moving parts, SSDs avoid both the risk of mechanical failure and the mechanical delays of HDDs. Therefore, SSDs are generally faster and more reliable. The catch is the cost: SSDs are currently much more expensive than HDDs.

Samsung 1.8-inch SSD

(Credit: Samsung)

There are also concerns about wear. That is, flash has the potential to wear out after tens (or hundreds) of thousands of write cycles.

This characterization, however, is too simplistic, according to Michael Yang, flash marketing manager at Samsung. A flash device that is rated at 100,000 write cycles, for example, can write 100,000 times "to every single (memory) cell within the device," Yang said. In other words, the device doesn't write to the same cell over and over again but spreads out the writes over many different cells. This is achieved through "wear leveling," which is carried out by the SSD's controller, he said.

This would make it virtually impossible to wear out a flash chip. Yang said a pattern could be perpetually repeated in which a 64GB SSD is completely filled with data, erased, filled again, then erased again every hour of every day for years, and the user still wouldn't reach the theoretical write limit. He added that if a failure ever does occur, it will not occur in the flash chip itself but in the controller.

On another topic, Yang cited explosive demand in the enterprise server market that caught his company by surprise. "At first it just sounded like an interesting idea," he said. But then demand took off. As Yang explained, companies like Citibank and American Express peg server performance on IOPS or input/output operations per second. "HDDs do 120 to 150 IOPS. SSDs 10,000 to 30,000 IOPS." Because of this overwhelming speed advantage many large corporate customers are opting for SSDs, despite the significant price premium SSDs command compared with HDDs.

Regarding cost, Yang expects to see a 35 percent to 45 percent year-to-year drop in SSD prices. This will be a welcome relief since 64GB SSDs currently can add as much as $900 to the price of a notebook PC.

In the third quarter, Samsung is slated to bring out a 128GB SSD based on MLC (multi-level cell) technology--which uses multiple levels per cell to allow more bits to be stored. But the company sees even larger-capacity SSDs, ranging all the way up to 250GB, possibly before the end of the year.

The company is also working with notebook PC makers to design ultrathin notebooks with SSDs that can fit into potentially even thinner designs than the 0.76-inch thick MacBook Air, which uses SSD.