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%.
Why?
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.
Use SCP_ LINUX_BANDWIDTH_30
/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.