I recently saw a PBS show about the future green Data Center's being run on DC, interesting stuff.
I know SUN for one is working on it with one of the National Labs here. http://hightech.lbl.gov/dc-powering/ -----Original Message----- From: Peter van Houten [mailto:[email protected]] Sent: Thursday, April 02, 2009 5:08 PM To: NT System Admin Issues Subject: Re: OTish: Googles Servers That would be an interesting experiment Ben...in national grid design, DC distribution is particularly inefficient for obvious reasons but maybe on a Google scale it is justified for some reason. It is indeed possible to run a stock-standard computer PSU from a suitable number of batteries connected in series. The first stage in a PC PSU ("switcher" or "whistler" in design parlance) is a rectification stage from the AC input to DC. That power is then used to drive an oscillator at about 50KHZ which, after amplification is stepped down to the requisite +12V with a small transformer. . So, it doesn't matter if the input is AC or DC and whether you like it or not, it will be converted to AC (albeit at the high-efficiency 50KHZ) before being converted back to DC. But I doubt that they are using a battery plant (for cost and scale reasons). I would be interested in the Google DC plant if you ever find that link. I'm too tired to look for it now... -- Peter van Houten On the 03/04/2009 01:11, Ben Scott wrote the following: > On Thu, Apr 2, 2009 at 6:16 PM, Peter van Houten<[email protected]> wrote: >> . The power supply claims an input voltage of "200-240vac". When did you >> folks on the other side of the pond raise your voltage? > > I seem to recall that Google was experimenting with plant DC > distribution to commodity PC hardware, and they had discovered that if > you feed a DC battery into the input of a 240 VAC power supply, it > worked. I don't recall what the battery voltage was. This also might > be something completely different; I'm just speculating. > > The advantage of an all DC power system is that you don't waste > money converting from DC to AC and back again, like you do with a > conventional UPS. You just have a giant battery plant as the primary > power source. AC is used just to keep the battery charged. If AC > fails, there's no UPS switch-over; the batteries just stop charging > for a little while. The telco's figured this out decades ago; all > their equipment runs on 48 VDC. > >> . Lack of display and audio sockets, even though the PCB is designed for >> these connectors. > > I'm guessing their "custom" motherboard is really semi-custom, i.e., > based on a reference design and tweaked as needed. Even just leaving > off an IC can save significant money when you buy motherboards by the > thousands. > >> . Keyboard, mouse, USB, LAN and 9 pin serial ports. Serial port??? > > As someone else said, that's almost certainly for the system > console. Linux ain't Windows; it doesn't need a graphics card. > Again, if you're doing tens of thousands of systems, the cost savings > can be substantial. Not only are serial console boxes cheaper than > KVMs, they save by not buying graphics ICs and not powering graphics > ICs. Plus serial can go tens of feet without signal degradation, > unlike VGA and PS/2. No need to put a KVM in every server rack. > >> I've read that Google use Linux; any guesses how much RAM in those 8 >> sticks? If it is circa 2007, probably 4GB? > > It prolly depends on whether Google's software is bound by I/O, CPU, > RAM, or whatever. They've got the money and the situation where if, > e.g., 8 GB would make more sense, it would pay off to do that. Linux > doesn't have all the memory limitations that Windows does, so that > wouldn't be an issue. Even 32-bit Linux can handle more than 4 GB of > RAM with PAE. But I'd guess Google is running 64-bit Linux, which has > been around since at least 1996, and was running on AMD64 from day > one. > > Google's in a situation where, even if they weren't mortal enemies > of Microsoft, they'd prolly go with Linux or another free Unix. > Hundreds of thousands of nodes, so economies of scale pay off in the > millions of dollars. All custom software, so no need to worry about > running apps that only run on 'doze. So by leaving out hardware that > Windows needs but *nix doesn't, they save on both equipment and > operating costs. They can spend man-years tuning and modifying the OS > for the absolute best performance for their application, well beyond > anything you can do with Windows. Plus all the license fees they > save. > > Of course, that's a somewhat unique situation, but I don't doubt > that it worries Microsoft anyway. There's lots of big companies with > big IT operations who might get ideas Microsoft wouldn't like. > > -- Ben ~ Finally, powerful endpoint security that ISN'T a resource hog! ~ ~ <http://www.sunbeltsoftware.com/Business/VIPRE-Enterprise/> ~ ~ Finally, powerful endpoint security that ISN'T a resource hog! ~ ~ <http://www.sunbeltsoftware.com/Business/VIPRE-Enterprise/> ~
