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Sync Your Data without the Cloud

New software lets you rouse a sleeping PC to retrieve data remotely.
February 22, 2012

Files on a home computer could soon be accessible from anywhere, even when the computer holding them is switched off, thanks to a prototype file-synching system developed at Microsoft’s research labs.

The system is designed to demonstrate an alternative to a growing array of cloud services. “One of our underlying principles is that you don’t always want to put all of your data in the cloud and give it to Google or some other corporation,” said Michelle Mazurek, of Carnegie Mellon University, presenting the technology at the Usenix File and Storage Technology conference in San Jose, California, last week.

Cloud systems can synchronize data between computers to provide access from anywhere, but users have to plan in advance which data they want to sync, and they have to trust a third party with their files.

Mazurek and researchers at Microsoft’s labs in Cambridge, U.K., built an alternative in the form of a simple application that makes all the data on one of a person’s computers visible and accessible from any of their others. The user’s devices act as personal cloud servers, and the software, called ZZFS, uses a novel hardware trick to wake up desktop and laptop computers that are in standby or sleep mode. This means that a file left on a closed laptop sitting on the couch at home can be retrieved from work.

A user can use the Windows Explorer file browser to see all the files and folders on other computers with ZZFS installed. Applications like Microsoft Office and iTunes can open those files normally, once they have been retrieved over the Internet.

A piece of hardware called Somniloquy is the reason this system works. The USB device, which acts like a smarter version of an ordinary network card that connects a computer to the Internet, can wake a sleeping computer and retrieve data from it before powering it back down. It has its own low-power processor and a few gigabytes of storage to cache files sent its way while a computer wakes up.

Mazurek believes that the overall design of ZZFS can be more accommodating of the spontaneous—some might say disorganized—way most people manage data spread across many devices. “Users don’t always know or plan what they need to have ahead of time,” she said, alluding to the fact that cloud services cannot sync all of a person’s data, so users must choose what is backed up.

Once a file grabbed from another ZZFS device is modified, the original is updated to reflect any changes. One advantage of ZZFS’s design is that data is downloaded even while devices are powered down. “If I’m switching between my laptop and tablet, and close the laptop, they’re never on at the same time,” says Mazurek. “If my data was on the cloud, I might have to wait a while for that data to come down.”

The researchers plan to create apps for phones and tablets; because those devices are rarely switched off, such apps could easily act like a PC equipped with one of the Somniloquy network cards, said Mazurek.

Although ZZFS manages to sync files without relying on the cloud, trials have shown that grabbing data from a sleeping device can take around 20 seconds because it takes a while for a Somniloquy card to wake a device. Mazurek acknowledges that this isn’t exactly speedy, but if data is crucial, then a short wait might be worth it. If ZZFS were proactive in fetching, say, music files, it could allow playlists of media from remote devices to play without a hitch, she said.

As Intel and other PC makers push laptops to become more like tablets, rapid startup times and “instant” waking from sleep have become important features for new PCs. “We think this [startup time] is coming down. Newer systems are on the order of 10 to 15 seconds to stand by and then resume, and we think that’s going to improve,” she said.

Yuvraj Agarwal, a researcher at the University of California, San Diego, led the original work that created the Somniloquy design, originally intending it as a way to save energy. But he believes the general design could become commercial reality, citing the way laptop manufacturers have experimented with “instant on” modes that rely on separate, low-power systems not unlike Somniloquy.

“There were some laptops that had a separate ARM processor with a completely different OS, such as Linux, in addition to the main system running Windows, which provided a mechanism to fast-boot and check e-mail, etc., quickly at lower energy,” explains Agarwal. “These two separate systems are of course not integrated together, as Somniloquy proposes, but you are starting to see a bit of this.”

Agarwal is currently working on a software-only version of Somniloquy called SleepServer that has centralized servers stand in for many sleeping PCs to save energy in buildings.

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