Hi, Running a bunch of CentOS servers on 2U supermicro equipment, usually with 8 drives on Adaptec SmartRAID V or LSI Megaraid. In designing a rack in a data center, the question arises as to how to measure the amperage the server uses, prior to investing in power drops that actually do that for you, even remotely, for about $260.00-300USD per unit. This number is the important one these days in determining rack/datacenter design. So the geek question is, "what do you use, from radio shack, or elsewhere, to accomplish this one time measurement *before* you implement a design"? Even deeper, is there an open-source equivalent to some of the software-based solutions that purport to be able to give a reading on amp usage. Just curious if you have a similar server-type, (supermicro=very popular), what your measurements have been. -karlski
Karl R. Balsmeier wrote:> Hi, > > Running a bunch of CentOS servers on 2U supermicro equipment, usually with > 8 drives on Adaptec SmartRAID V or LSI Megaraid. > > In designing a rack in a data center, the question arises as to how to > measure the amperage the server uses, prior to investing in power drops > that actually do that for you, even remotely, for about $260.00-300USD per > unit. This number is the important one these days in determining > rack/datacenter design. >I use the Radio Shack Amp meter. It has an inductance jaw that you put over ONE wire to the device. This means you need a place on the circuit that separates the hot and neutral wires. I have a special rig: Mail plug - separate wires - Female receptacle. Of course I have to unplug the device, put this rig in, test, then put things back.
Robert Moskowitz wrote:> Karl R. Balsmeier wrote: >> Hi, >> >> Running a bunch of CentOS servers on 2U supermicro equipment, >> usually with 8 drives on Adaptec SmartRAID V or LSI Megaraid. >> >> In designing a rack in a data center, the question arises as to how >> to measure the amperage the server uses, prior to investing in power >> drops that actually do that for you, even remotely, for about >> $260.00-300USD per unit. This number is the important one these >> days in determining rack/datacenter design. >> > I use the Radio Shack Amp meter. It has an inductance jaw that you > put over ONE wire to the device. This means you need a place on the > circuit that separates the hot and neutral wires. I have a special > rig: Mail plug - separate wires - Female receptacle. Of course I > have to unplug the device, put this rig in, test, then put things > back. >That's one way to measure the current, then multiply by the input voltage to get watts. I think a better way is to determine the max current that the system will use. If you have a 500 watt PSU, assume 85% efficiency, then by using the input voltage you can calculate the max input power the server is going to draw. I'd design the datacenter to support the max power level the server will need, not just what it takes to run the thing. Start up will draw the most power, approaching the max power output of the PSU, then it'll lower some once all the drives are up and spinning. It's somewhat an art, but you can get reasonably close to the entire power draw of your rack. In a pinch, I've added up all the UPSes and told the electrician 12000VA. They'll know what to do with that number. HTH Mark
On Tue, 1 Aug 2006 at 6:55pm, Karl R. Balsmeier wrote> Running a bunch of CentOS servers on 2U supermicro equipment, usually with > 8 drives on Adaptec SmartRAID V or LSI Megaraid. > > In designing a rack in a data center, the question arises as to how to > measure the amperage the server uses, prior to investing in power drops > that actually do that for you, even remotely, for about $260.00-300USD per > unit. This number is the important one these days in determining > rack/datacenter design. > > So the geek question is, "what do you use, from radio shack, or elsewhere, > to accomplish this one time measurement *before* you implement a design"?Kill-A-Watts a pretty darn popular on the beowulf list -- it seems like everyone has one. Thinkgeek has 'em for $30. -- Joshua Baker-LePain Department of Biomedical Engineering Duke University
> Running a bunch of CentOS servers on 2U supermicro equipment, usually with > 8 drives on Adaptec SmartRAID V or LSI Megaraid. > > In designing a rack in a data center, the question arises as to how to > measure the amperage the server uses, prior to investing in power drops > that actually do that for you, even remotely, for about $260.00-300USD per > unit. This number is the important one these days in determining > rack/datacenter design. > > So the geek question is, "what do you use, from radio shack, or elsewhere, > to accomplish this one time measurement *before* you implement a design"?Easy. Get any modern UPS that will talk to your OS (or the OS on another nearby computer), plug in a server, and look at the UPS display. All the UPSs I have used lately will tell you what the load they are providing is, either is watts or in amps. Ted Miller Elkhart, IN Centos NewNewbie