HDFS NFS Gateway 無法啟動、掛載失敗問題
如遇到NFS啟動失敗，或者其他機器掛載NFS失敗，錯誤字樣有如下
掛載失敗關鍵字：
mount.nfs: requested NFS version or transport protocol is not supported
啟動失敗關鍵字：
WARN org.apache.hadoop.oncrpc.RpcProgram: Invalid RPC call version 4
NFS service is already running on this host. Please stop the NFS service running on this host before attempting to start the NFS Gateway role.
Started listening to TCP requests at port 2049 for Rpc program: NFS3 at localhost:2049 with workerCount 0
ShutdownHook ‘NfsShutdownHook’ failed, java.lang.RuntimeException: Unregistration failure
關鍵字樣，沒有portmap or rpcbind服務，所以後續工作無法進行：
No portmap or rpcbind service
工作執行機制為：
HDFS NFS Gateway工作需要依附 rpcbind 服務，所以啟動前需要確定rpcbind服務正常開啟。 service rpcbind start
但是HDFS NFS 服務會與系統自帶的NFS服務衝突，所以在啟動前需要關閉系統自帶的NFS服務。service nfs stop