Nanotech - The Circuits Blog

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.

Samsung Electronics has begun mass producing 64GB solid state drives (SSDs) with a new high-performance interface and will begin shipping the drive to major notebook PC suppliers, the company announced Friday. This follows last month's announcement of plans to bring out a 128GB SSD.

Samsung SATA-II SSD

(Credit: Samsung)

The new Serial ATA (SATA)-II SSD is able to read data at 100 megabytes per second (MB/sec) and write it at 80MB/sec, 60 percent faster than SATA I drives, Samsung said.

Dell will be one of the first takers. "Today, I wanted to let our customers know that in the coming weeks we will be launching the Dell Flash Ultra Performance SSD based on Samsung's SATA II-SSD technology, available in 32GB and 64GB capacities, which will leave traditional notebook hard drives in the dust," according to a post on Dell's Direct2Dell blog.

"Our labs benchmarked this drive in a Latitude notebook and saw a 35 percent overall system performance increase over a standard 2.5-inch 5400rpm notebook hard drive using SYSmark '07. That's even more impressive when you realize that the difference between standard 5400rpm and performance 7200rpm drives (in the same generation) is 10 percent on average," Dell said.

Alienware is also slated to use the SSDs.

Last month, Samsung announced the development of a 128GB SSD that it will produce this year in 1.8- and 2.5-inch versions for notebook and desktop PCs, as well as other mobile applications. That drive offers a data writing speed of 70MB/sec, the industry's highest for multi-level cell-based SSDs (which uses multiple levels per cell to allow more bits to be stored), the company said. It reads data at 100MB/s. These published speeds exceed 2.5-inch hard drives used in mainstream notebooks.

SSDs are generally much faster than hard drives at reading data (which is what computer users spend most of their time doing) and slower at writing data to disk. But, overall, SSDs are becoming popular in niche markets because they have advantages crucial for ultra-small gadgets and ultra-thin notebook PCs: they weigh less, use less power, generate less heat, and withstand shock better. The new SATA II SSD can resist up to 1500 Gs of shock in a half millisecond compared to a shock resistance rating of 300 Gs in 2 milliseconds for a typical HDD, Samsung said.

As a caveat, it should be noted that flash technology--which SSDs are based on--has a skeleton in the closet. Flash has limited write cycles. That is, flash drives have the potential to "wear out" after hundreds of thousands of write cycles. File systems that spread the writes over the device can extend the life cycle but it's still an issue that corporate users of flash storage have brought up in the past. It remains to be seen if this actually becomes a problem later in notebooks with SSDs such as the MacBook Air and Eee PC.