Last month I made a post about using rrdtool and ruby to graph hard disk temperatures. I recently had some hardware trouble and something with permissions went crazy. Today I took the time to look into the problem and fix it.
The /dev/hd[egik] device nodes were owned by root:disk and 660. However, the hddtemp binary was trying to do some restricted ioctl operations. Even though the binary was setuid and my non-root user was in the disk group I couldn’t access the disk to get the temperatures.
I found out that there is a hddtemp daemon which can query the disks for my unpriveleged user.
The daemon listens on a TCP port and provides output like this:
|/dev/hde|ST3160811AS|39|C||/dev/hdg|ST3160811AS|40|C||/dev/hdi|ST3160811AS|38|C||/dev/hdk|ST3160815AS|39|C|
Should be easy to modify my disk_temperature.rb to connect to that port and parse the data.
Now my temperature graphs will have new data (as soon as the change is made).
Since I got to North America I have wanted to put my system under better monitoring. It’s got four active hard disks (and a fifth powered, not active) hard disk in an IcyDock MB-455SPF 5-Bay Internal SATA Drive Enclosure (Manufacturer site, icydock.com, seems offline so link to where I bought it!) with the four active disks plugged into a HighPoint RocketRaid 1640 SATA controller.
I can easily use S.M.A.R.T. to monitor the temperature and the hddtemp Linux utility to get the temperatures of the disks.
It’s easy to use a crontask to poll the disks and to stuff the temperatures into an rrdtool database. I drew much inspiration from Martin Pot’s Perl script to do the same thing but implemented my own in a Ruby Rake task using the woefully undocumented RubyRRDtool gem and a custom hddtemp wrapper class to get the temperatures.
The similarities between my Rake task and Martin’s RRDtool-fu is obvious, however I wanted an hour graph too and so I added it in on line 17.
My next task is to combine the temperatures (lines) of all four disks into a single graph to get a feel for the overall temperature of the disks on one image.
The graphs can be seen at my personal website.
