USB 3 chip will bring RAID to external drives

IDG News Service - Symwave, one of the first companies to design silicon for USB 3.0, is revealing more details about its SOC (system on a chip) using the high-speed standard at the Hot Chips conference on Monday.

USB 3.0, which debuted last November, is designed to provide throughput as high as 5Gb per second (Gbps), up from just 480Mbps for USB 2.0. Symwave says its USB 3.0 SOC can be used in external storage devices that ship data as fast as 500MB per second.

Symwave is trying to tackle the same problem plaguing many consumers and enterprises as they use more high-definition multimedia content and have to save more data in general. Demand for storage capacity continues to rise, and backing up that data from a laptop or desktop to an external drive can take hours. USB 2.0, nearly ubiquitous on PCs and portable consumer electronics today, can be a barrier.

"You're pretty much communicating through a straw," said Gideon Intrater, Symwave's vice president of solutions architecture. The SATA (Serial Advanced Technology Attachment) I/O protocol used with most hard drives can transport about 300MB per second, while USB 2.0 typically delivers just 20MB or 30MB per second, he said. "USB 2 was good as long as you had 100GB on your hard drive, but now it's just way too slow."

By way of comparison, a 25GB high-definition movie would take 13.9 minutes to transport over USB 2.0 and just 70 seconds with the new standard, according to the USB Implementers Forum. The contents of a 1GB thumb drive could be transferred in 3.3 seconds, versus 33 seconds previously.

The SOC that Intrater will discuss on Monday will boost that performance up to and beyond the top speed of SATA. It's a chip for external storage devices that includes several key functions for either HDD (hard disk drive) or SSD (solid-state drive) units. The chip will allow OEMs (original equipment manufacturers) of storage devices and enclosures to offer speeds as high as 500MB per second because it includes support for RAID 0 configurations. Using RAID, the system maker can build an enclosure with two drives and either feed data faster by addressing both drives at once, or feed the same data to both drives so one is a mirror of the other, Intrater said.

RAID hasn't been a realistic option with USB 2.0 because just one SATA drive can easily saturate the USB connection, according to Intrater. In addition, USB 2.0 has been limited in the kinds of devices it can power by itself. USB 3.0 can carry as much as 900 milliamps, up from just 500 milliamps for USB 2.0, he said. That will make it easier to power a portable RAID array of two drives, as well as to power faster-spinning HDDs than before and to charge some smartphones and other devices that the older standard couldn't fill up, Intrater said.

Reprinted with permission from

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