USB flash memory drives are experiencing an increase in product failures as a result of quality-control problems, and the wildly popular replacements for floppy disks could be facing other problems related to fragmentation, according to industry experts.

Recent Gartner numbers indicate that 88.2 million USB flash drives were shipped in 2005, and 115.7 million will be shipped in 2006. While these portable nonvolatile storage units don't last forever, single-level cell NAND flash drives are commonly acknowledged to last for an average of 100,000 read-write cycles, which is an infinite amount for most users.

However, according to Alan Niebel, a semiconductor analyst at Web-Feet Research, fragmentation is becoming more of a threat, especially as USB flash memory sizes grow. "Flash disks will soon encounter fragmentation problems and a need to arrange the data in order to prevent problems," Niebel said.

"Like mechanical disks, flash disks have their own technical limitations, so it will be wise to measure the fragmentation level on flash disks in order to avoid unnecessary writes on the media," he added.

Koby Biller, founder of the Israeli software firm, Disklace, also believes USB flash drives need to be measured for fragmentation and then defragged before the damage to memory reaches a point of no return. A former systems engineer with IBM, Biller has 27 years experience working on a variety of IT systems.

"It's like cholesterol, people don't measure it until their life spans start to be shortened," Biller said.

According to IDC, fragmentation occurs when documents are created and then saved or erased.

When a file is first created and saved onto a hard drive or disk, it is stored in contiguous clusters. When the file is later recalled, the head, which reads the information, moves from one cluster to another on a single track. As files are added, they are also set in contiguous clusters. When files are erased, the cluster space they occupied becomes available and is filled as new files are created.

When the new files are larger than the available contiguous space, the information in those files gets broken up and is randomly placed on the disk, and files start to become fragmented. Eventually, the situation deteriorates to the point where performance is severely impacted and files take disproportionate long times to open.

Biller said that problems related to fragmentation are not communicated to consumers, so consumers aren't defragging their flash drives. While Disklace may have a stake in defragmentation because it sells software that can measure the amount of fragmentation in flash drives, Biller is not the only one issuing warnings.

Fragmentation not the issue

Some industry analysts, such as Gartner's Joe Unsworth and IDC's Celeste Crystal, aren't as concerned about USB flash drive fragmentation. Asked if he believes if defragging flash memory is a good idea, Unsworth said simply, "I've not heard of it."

"It's not something that has become a very big issue with the USB flash drive market," Crystal added.

But a problem that is becoming bigger for this technology is manufacturing quality control, according to a recent report by the Australian firm Payam Data Recovery (PDR). Cases of faulty USB flash drives are on the rise the point where there has been a 300 percent year-over-year increase in cases of USB drives that have "suddenly stopped working" as a result of "faults, misuse and an increasing number of poorly manufactured devices on the market," according to PDR's study.

"I would expect that you would see an increase in problems with USB flash drives because they're much more pervasive and there are a lot of companies that are [manufacturing] them these days," Unsworth said. Many of the companies producing flash memory are based in Taiwan, Singapore and China, and Unsworth said that Asia-Pacific distributors are trying to differentiate themselves on price, which is forcing many market players to follow suit. As a result of this price pressure, some companies are selling products based on inferior flash memory, he said.

Steffen Hellmold, president of The USB Flash Drive Alliance, said he doesn't believe that fragmentation presents a problem with flash memory, but he does agree that quality control has been an ongoing issue. "There are issues around endurance and longevity," he said.

"There is a trade-off, obviously, between data endurance, longevity, as well as cost, and you need to know the differences to make the right choice of what it is you want," Hellmold added.

Lexar recalls JumpDrives

Hellmold, who is also general manager of the OEM products business at flash drive manufacturer Lexar Media, said there have been "some substandard nonvolatile memory being used by some manufacturers that caused data losses in specific geographical regions."

"For the most part as I understand it, it has been the Asian region as far as people actually experiencing some data loss." Hellmold said.

Lexar has encountered quality control problems of its own of late (see "Lexar recalls dangerous flash drives "). As of Sept. 8, it was running a public notice of a limited recall of its JumpDrive Firefly and JumpDrive 1GB Secure II flash memory drives, saying it had identified a "potential issue" in the JumpDrive products sold between April 1 and May 31, 2006, in the U.S.

According to Lexar, "Certain configurations of these products have a potential to overheat, creating potential risk of injury and property damage. The potential for the products to overheat was identified by Lexar during testing, and no reports of overheating during use have been reported flash drive owners. All affected products shipped to retailers have been returned to Lexar and most retail stores have already received replacement products and are actively selling them, Lexar said.

Asked how consumers can ensure they are buying the highest quality flash memory drives, Hellmold said it is wise to look for logo certifications and independent product test reports. Unsworth answers the same question by urging consumers to look for brands with widespread recognition such as SanDisk and Kingston Technology Company. He also advises consumers not to go for the lowest price unless it's from a reputable source. "If you see a product that is too good to be true in terms of price," he said, "maybe it is."