<p>I'm trying to find a reasonable log level in which control plane component (e.g. kubelet) would print enough information helping debug when a problem happens, and also the log file size wouldn't be too large, causing any potential disk io problem. </p>

<p>K8s log level flag --v is not well documented,  the most helpful doc I can find is <a href="https://kubernetes.io/docs/reference/kubectl/cheatsheet/#kubectl-output-verbosity-and-debugging" rel="nofollow noreferrer">this</a> , it is about kubectl's --v falg, so I'm not sure if it's correct with kubelet, or apiserver, the description of log level 5 is also missing.</p>

<p>Is there any other docs? Or is there any best practice of --v setting?</p>

<blockquote>
  <p><code>kubectl --v=5 - Trace level verbosity</code> is <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/sig-instrumentation/logging.md" rel="nofollow noreferrer">documented here</a></p>
</blockquote>

<p>On a production cluster i will <strong>recommend keeping default log level</strong>, and only change to more verbose logs when needed to debug cluster level issues (and return the log verbosity back to default after any such troubleshooting is done)</p>

<blockquote>
  <p>to change kublet verbosity you can append <strong><code>/var/lib/kubelet/kubeadm-flags.env</code></strong> file with --v=5 flag and restart kublet to read to required verbosity .</p>
</blockquote>
