[mrtg] Graphing disk iowait on Debian using mrtg and routers2

[Steve Shipway]

> I'm trying to graph iowait on Debian but having trouble finding
> examples. Is it best to use an
> iostat bash script or the SNMP counter (.1.3.6.1.4.1.2021.11.54.0)?
> 
> The SNMP counter seems to be an ever increasing value. I thought it
> might be the number
> of seconds the CPU has waited for, but I'm not sure how to use this
> value?

If I remember right, this is a counter of CPU seconds.  The problem you get is when you have multiple CPUs and need to normalise this to a percentage.... 

Graph it as a normal counter, which results in a calculated seconds per second, and use a Factor[] of 100 to give you a percentage on a single-CPU system.  If you have a dual CPU system, use a factor of 50 (100/cpus) and so on, and set ShortLegend[] to %.

Steve