k8s提供多种volume接口，其中local 和host path是容易混淆的两个接口。下面这篇文章解释了两者的区别：
https://groups.google.com/forum/#!topic/kubernetes-users/68Yvm8ZkztI
关键内容：
Both use local disks available on a machine. But! Imagine you have a cluster of three machines and have a Deployment with a replica of 1. If your pod is scheduled on node A, writes to a host path, then the pod is destroyed. At this point the scheduler will need to create a new pod, and this pod might be scheduled to node C which doesn't have the data. Oops!
Local volumes fix this by ensuring a pod is scheduled to the machine where the data exists.