Try the Dallas/Maxim 1-wire system. They have serial port controllers with an RJ11 jack so you can use a phone cable to the sensor. I got one of their temp sensors and a cheap RJ11 jack from Radio Shack and had a remote temp sensor. They use a simple serial protocol and some of the controllers are "smart" like the DS9097U $28 or so for the controller: http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2983 http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2923 For temperature DS28EA00: http://www.maxim-ic.com/quick_view2.cfm/qv_pk/5355 On Fri, Feb 26, 2010 at 2:02 PM, nate <centos at linuxpowered.net> wrote: > Dominik Zyla wrote: > >> You have right. While you checking sensors from few machines, you can >> see the trend. Gotta think about changing the way of temperature monitoring >> here. > > Myself I wouldn't rely on internal equipment sensors to try to > extrapolate ambient temperature from their readings. Most equipment > will automatically spin their fans at faster RPMs as the temperature > goes up which can give false indications of ambient temperature. > > I do monitor the temperature of network equipment, but also have > dedicated sensors for ambient readings. Already saved us some pain > once, opened up a new location in London last year and the ambient > temperature at our rack in the data center was 85+ degrees F. The > SLA requires temperature be from 64-78 degrees. Alarms were going off > in Nagios. > > The facility claimed there was no issue, and opened up some more > air vents, which didn't help. They still didn't believe us so they > installed their own sensor in our rack. The next day the temperature > dropped by ~10 degrees, I guess they believed their own sensor.. > > http://portal.aphroland.org/~aphro/rack-temperature.png > > People at my own company were questioning the accuracy of this > sensor(there was only one, I prefer 2 but they are cheap bastards), > but I was able to validate the increased temperature by comparing > the internal temp of the switches and load balancers were > significantly higher than other locations. Though even with the > ambient temperature dropping by 10+ degrees, the temperature of > the gear didn't move nearly as much. > > The crazy part was I checked the temperature probes at my former > company(different/better data center) and the *exhaust* temperature > of the servers was lower than the *input* temperature from this > new data center. Exhaust temperature was around 78-80 degrees, > several degrees below the 85+. > > It seems the facility in London further improved their cooling > in recent weeks as average temperature is down from 78 to about > 70-72 now, and is much more stable, prior to the change we > were frequently spiking above 80 and averaging about 78. > > Also having ambient temperature sensors can be advantageous in > the event you need to convince a facility they are running too > hot(or out of SLA), as a tech guy myself(as you can probably > see already) I am much less inclined to trust the results of > internal equipment sensors than a standalone external sensor > which can be put on the front of the rack. > > nate > > > _______________________________________________ > CentOS mailing list > CentOS at centos.org > http://lists.centos.org/mailman/listinfo/centos >
