Wade Hampton wrote: > 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 >> >> > _______________________________________________ > CentOS mailing list > CentOS at centos.org > http://lists.centos.org/mailman/listinfo/centos > > +1 ChrisG
