Tiny Web Services

robk — Fri, 07 Mar 2008 01:31:00 GMT

I mentioned the other day that I had run into Feng Zhao, principal researcher in the Networked Embedded Computing group, who was looking particularly happy at the moment. Well, Feng has been demonstrating the reason for his delight over the past three days: a set of small, wireless sensor devices, branded with the Microsoft Research logo, that he and his group plan to utilize in a variety of settings.

"This is an example of a sensor that we use for research and we plan to put into a data center," Zhao says, holding one of the devices up for inspection. "The sensors currently in data centers are a different form factor. This one just got designed. It senses temperature and humidity, the kinds of parameters one cares about in a data center."

The sensors are special, Zhao says, because of their size, their functionality, and their energy efficiency.

"We're working on making sensors easier to manage and interoperable with other devices," he says, "and to make the devices speak the kinds of language and protocols that computers on the Internet speak. For example, on the Internet, computers talk in terms of Web services, TCP/IP, HTTP. But these are designed for much bigger machines, and this one only has 4K of memory. We want to shrink these very big things onto this device with a very small memory and processor, and, furthermore, use as little energy as possible: two AA batteries for a year."

It's part of a research project called Tiny Web Services, designed to develop sensor nets and Web-service techniques that can fit onto these tiny 4K sensors. The sensors are programmed to go to sleep when not needed to send information.

"Web servers anticipate a set of requests, and they have to respond immediately," Zhao explains, "so they stay on all the time, waiting for requests. This one uses AC currency, and Web services can register events to make it turn itself on. A number of these techniques are being used to make the footprint of Web-service processing much smaller and simpler but still comply with the standards of the Internet so the device can talk to other devices."

Zhao's group is one of the first to address this area, and its devices are among the smallest--and least expensive--to talk in terms Web services can understand. Beyond their small footprint, they also contain technology that is advancing the state of the art.

"By building our own devices," Zhao says, "we actually are building a stack of software. We own all the drivers, and we can program. Our goal is to develop this into a reliable system, and we're also interested in making them available to academics, to help people building applications for the environment, for conservation, or for energy savings. If you look at what's currently available, some of those devices are not as reliable or as easy to program as we'd like."

With that, he was smiling again. These days, it seems, Feng Zhao just can't help himself.

Rick Rashid, senior vice president of Microsoft Research, shows one of Feng Zhao's new wireless sensors to an audience of invited guests during Tuesday's TechFest keynote speech.

Auto Shift: Energy-Aware Server Provisioning

robk — Wed, 05 Mar 2008 02:15:00 GMT

Green, as we now know, is, indisputedly, the new black. Seems like you can't turn on the television or pick up a newspaper to read about the latest green initiative. Lots of people are talking.

Feng Zhao is doing something about it.

Zhao's Networked Embedded Computing group is showing a TechFest demo called Auto-Shift: Energy-Aware Server Provisioning, which addresses server resource management for Internet services, such as Live Messenger and Hotmail. Data centers for such services require potentially expensive decisions about how many computers to allocate and how those are deployed.

"No. 1," Zhao says, "you have to buy the servers. No. 2, once you buy a server, you have to manage it. And third, you have to have an infrastructure, such as power supply. In this particular study, we looked at the power usage of the servers that are running one of our largest Web services. If you look at the load as it varies over the course of the day, it peaks around noon and slows down around midnight. That clearly shows that not all the servers are needed all the time. Can we shut down some of the servers? Can we actually save energy?"

Initially, Zhao and colleagues thought the challenge might be straightforward. But complications arose. With a Web service such as Messenger, users are serviced continually. When servers are turned off, users lose access, and when they sign back in, they create a spike in the data-center load.

"We have developed a set of techniques that allow us to intelligently forecast when a load is going to spike," Zhao says, "and to provide a period of buffer time so that we gradually shut down machines--and only shut down machines when the load on the machine is below some small threshold. So we don’t have to migrate too many users, which, in turn, would create too many spikes in the load. The techniques that we have been developing are different ways of managing that process of gradually ramping down a server--and at the same time having some knowledge about what’s coming and actually prepare enough resources."

Some techniques, though, save more energy, some slightly less.

“If you want to be aggressive about saving energy, you are going to incur some penalties," Zhao says. "Maybe the response time will be longer. We’re looking at these tradeoffs. If you care more about energy, it will have to be at the price of a little more degraded user experience. Or you can provide a very good user experience, but the energy saving might be a little bit less. That’s a very interesting set of findings."

Auto-Shift is based on Messenger data over a period of 45 days running on machines used to emulate the Networked Embedded Computing's group's algorithm. Zhao says that algorithm can achieve energy savings of as much as 25 percent without significantly affecting the user experience.

"Energy savings are possible," he says, "but they require some careful scheduling, management, and predicting, and we have algorithmic smarts in the system that allows us to do this."

Work remains. The team needs to ensure sure that its algorithm works with other existing components. Other Internet services need investigation to see if the savings work in other scenarios. In the meantime, the server-provisioning work could prove even more beneficial.

"We also have all these sensors in the data centers," Zhao says. "Some of the machines work harder than others. If we can move the workload around, from hotspots to cool spots, the air conditioning doesn’t have to work as hard, because of the efficiency of cooling the hottest spots. If you move that workload and even out the temperature disparities, that means good energy savings. Incorporating environmental-sensor readings such as temperature and humidity, and couple that with smart scheduling and workload migration, and we believe we can even save more resources."

That sounds green, indeed--and economical, too.

"What it translates to," Zhao concludes, "is that you use less power and that, with these smarts, we can figure out that maybe we don’t need to buy that many machines to start with, because we can do the same work, with very little difference in performance, and actually run it on a smaller set of machines. Reduce energy cost and reduce hardware investment in the first place--that would reduce service cost, reduce staffing, and reduce the space you need to build."

TechFest Live! : Feng Zhao

Tiny Web Services

Auto Shift: Energy-Aware Server Provisioning