6: Bandwidth

Being on the network is half the battle – it’s good the Linux servers are on the net, but just as important is to ensure they have the needed bandwidth.

If network bandwidth is over 30%, you’ve got a problem.

Not 90%, 30%.


Same as waiting for a bus (or – never happened to you – a cop). It’s flood or famine.

In other words, while there often is not a lot of traffic to or from the network, when there is, there is a lot.

This is the one metric that is most often wrongly set.

If your bandwidth utilization is generally over 30% you need to adjust the network topology.


/proc/net/dev is used to determine the utilization.

As with CPU there can be sudden spikes in network utilization, so set “Post Event Only After Rule Is Broken” to 3.