It’s no secret that Facebook (s fb) stores a lot of data — 100 petabytes, in fact — in Hadoop, but how it keeps that data available whenever it needs it isn’t necessarily common knowledge. Today at the Hadoop Summit, however, Facebook Engineer Andrew Ryan highlighted that solution, which Facebook calls AvatarNode. (I’m at Hadoop Summit, but didn’t attend Ryan’s talk; thankfully, he also summarized it in a blog post.)

For those unfamiliar with the availability problem Facebook solved with AvatarNode, here’s the 10,000-foot explanation: The NameNode service in Hadoop’s architecture handles all metadata operations with the Hadoop Distributed File System, but it also just runs on a single node. If that node goes down, so does, for all intents and purposes, Hadoop because nothing that relies on HDFS will run properly.

As Ryan explains, Facebook began building AvatarNode about two years ago (hence its James Cameron-inspired name) and…

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Updated: As we reported earlier this year, PG&E is the first utility that has been piloting the smart thermostat collaboration between thermostat giant Honeywell (s HON) and energy software startup Opower. And some early results (collected by PG&E) are in: customers like using the smart thermostats and particularly like being able to remotely control the thermostat using their iPhone. However there were some issues in the trial’s recruitment and installation processes.

Remote control of the smart thermostat could prove to be one of the first smart grid applications that is a clear benefit to consumers. One of the major problems with smart meters is that consumers haven’t really seen the direct benefits (beyond savings) of having the smart meter installed at their homes — a lot of the benefits of smart meters are actually for the utility. But remote control of a thermostat is a service that even companies…

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