Sony 6X Blu-ray Writer USB Drive May Be Too Fast for PCs

Sony will launch an external Blu-ray Disc rewritable drive this month that can burn BD-R discs that support 6X speed, but users hoping for fast transfers might encounter a bottleneck in the form of their computer.

The 6X speed offered by the BDX-S500U when writing to single-sided discs translates into a write speed of 27MBps, according to the Blu-ray Disc specification. The drive connects to computers via USB 2.0, which has a theoretical maximum speed of 60MBps, but has been measured to run much slower in real-world tests.

Some of that speed is taken away by networking overheads built into the protocol, and more by inefficiences in many USB interface chips. A test earlier this year by Techworld found a USB 3.0 chipset, one of the first to support a new breed of faster USB connections, supported a maximum USB 2.0 write speed of just 11MBps. The speed is also shared among other peripherals on the USB bus, so could fall further.

Sony is bundling a 25GB single-sided 6X BD-R disc and CyberLink Media Suite 8 disc burning software with the drive, but the drive can also write to dual-layer 4X BD-R discs that hold 50GBs of data. It can also record to most of the common DVD and CD rewritable and writable formats.

Sony said the drive will be available this month, but did not announce pricing. However, several online retailers are already listing the drive for between US$214 and $240.

Martyn Williams covers Japan and general technology breaking news for The IDG News Service. Follow Martyn on Twitter at @martyn_williams. Martyn's e-mail address is martyn_williams@idg.com

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