Now I’m posting my Cacti templates and script to get these values so anyone can create this graph.
The peak of the graph topped out at 140Mbit while I’d been transferring data at around 600Mbit. It turns out that this is a limitation of 32-bit counters that overflow after 5 minutes.
So I decided to switch to 64-bit counters in Cacti. I ran my tests again and this time my graphs were a total mess. According to the graph I’d transferred multiple terrabytes of data in just 5 minutes.
So I’ve sent an email to HP to make them aware of this bug, I even received a response:
Thank you for using Hewlett Packard Customer Service.
This info has been send to the division and in a later Firmware update this issue will be adressed
unfortunatly there is no timeframe known for this fix yet.
Hewlett Packard Customer Service
Doesn’t sound very convincing, but I hope the next firmware release fixes this annoying bug.
My previous post about getting the temperatures of disks connected to an Areca raid array already noted that MRTG can only handle two datasources in a single graph.
With 5 disks in a system, this would force me to create 3 graphs, or 1 graph with the temperatures of the 4 disks connected to the RAID array averaged into a single line.
I’ve always wanted to move from MRTG to RRDtool, because RRDtool can handle multiple datasources per graph, and has more options.
However, I found RRDtool very hard to configure compared to MRTG. So I went looking for an alternative.
Cacti is a front-end for RRDtool, which makes it easier to create nice graphs. If you just want to graph routers, it’s even easier to configure than MRTG. But if you like to have custom stats, like the Areca HDD temperatures, it takes a little more work.
Cacti has some nice guides on how to create graphs and new input methods on their site, but even with those it took me quite some time to create my first graph.
I’ve been running my Areca RAID array for a few months now and I’m very pleased with it. The only thing that was bothering me was the lack of MRTG graphs for the attached disks.
The disk temperature is an important thing to monitor, because as Google pointed out, a high disk temperature has a significant effect on drive failure.
In Areca’s web interface you have total control over your RAID array. You can add/remove disks, create new arrays and do a check on existing arrays.
But it’s annoying to have to log in to this web interface just to check the temperatures of the disks. Also, it doesn’t come with nice graphs and history information. It just shows the current temperatures.
Areca has also made a CLI utility. Using this utility you can do the same things as in the web interface. I’ve used the CLI utility to generate the data needed by MRTG. MRTG can only handle 2 datasources in one graph. Having 5 disks total (1 bootdisk, 4 RAID member disks), I would need 3 graphs to monitor the disks. So I decided to create a little BASH script that would take the temperature of the bootdisk, and the average temperature of the 4 RAID disks and feed this to MRTG.