Merge pull request #11119 from medyagh/faq

site: update FAQ

site/content/en/docs/faq/_index.md

@@ -6,6 +6,44 @@ description: >
   Questions that come up regularly
 ---
 
+
+## How to run an older Kubernetes version with minikube ?
+
+You do not need to download an older minikube to run an older kubernetes version.
+You can create a Kubenretes cluster with any version you desire using `--kubernetes-version` flag.
+
+Example:
+
+```bash
+minikube start --kubernetes-version=v1.15.0
+```
+
+
+## Docker Driver: How to set the cgroup manager minikube uses?
+
+By default minikube uses the `cgroupfs` cgroup manager for the Kubernetes clusters, if you are on a system with a systemd cgroup manager, this could cause conflicts.
+To use `systemd` cgroup manager, run:
+
+```bash
+minikube start --force-systemd=true
+```
+
+## How to run minikube with Docker driver if existing cluster is VM?
+
+If you have an existing cluster with a VM driver (virtualbox, hyperkit, KVM,...).
+
+First please ensure your Docker service is running and then you need to either delete the existing cluster and create one
+```bash
+minikube delete
+minikube start --driver=docker
+```
+
+Alternatively, if you want to keep your existing cluster you can create a second cluster with a different profile name. (example p1)
+
+```bash
+minikube start -p p1 --driver=docker 
+```
+
 ## Does minikube support IPv6?
 
 minikube currently doesn't support IPv6. However, it is on the [roadmap]({{< ref "/docs/contrib/roadmap.en.md" >}}).