add mpath trouble shooting for pflex (#270)

content/docs/csidriver/troubleshooting/powerflex.md

@@ -21,6 +21,7 @@ description: Troubleshooting PowerFlex Driver
 | Driver install or upgrade fails because of an incompatible Kubernetes version, even though the version seems to be within the range of compatibility. For example: `Error: UPGRADE FAILED: chart requires kubeVersion: >= 1.21.0 <= 1.23.0 which is incompatible with Kubernetes V1.21.11-mirantis-1` | If you are using an extended Kubernetes version, please see the helm Chart at `helm/csi-vxflexos/Chart.yaml` and use the alternate `kubeVersion` check that is provided in the comments. *Please note* that this is not meant to be used to enable the use of pre-release alpha and beta versions, which is not supported. |
 | Volume metrics are missing | Enable [Volume Health Monitoring](../../features/powerflex#volume-health-monitoring) |
 | When a node goes down, the block volumes attached to the node cannot be attached to another node                                           | This is a known issue and has been reported at https://github.com/kubernetes-csi/external-attacher/issues/215. Workaround: <br /> 1. Force delete the pod running on the node that went down <br /> 2. Delete the volumeattachment to the node that went down. <br /> Now the volume can be attached to the new node.                   |
+| CSI-PowerFlex volumes cannot mount; are being recognized as multipath devices | CSI-PowerFlex does not support multipath; to fix: <br/> 1. Remove any multipath mapping involving a powerflex volume with `multipath -f <powerflex volume>` <br/> 2. Blacklist CSI-PowerFlex volumes in multipath config file |
 
 >*Note*: `vxflexos-controller-*` is the controller pod that acquires leader lease