Copying Data Using NFS

If NFS is installed on the MapR cluster, you can mount the MapR cluster to the HDFS cluster and then copy files from one cluster to the other using hadoop distcp. If you do not have NFS installed and a mount point configured, see Accessing Data with NFS and Setting Up MapR NFS.

To perform a copy using distcp via NFS, you need the following information:
  • <MapR NFS Server> - the IP address or hostname of the NFS server in the MapR cluster
  • <maprfs_nfs_mount> - the NFS export mount point configured on the MapR cluster; default is /mapr
  • <hdfs_nfs_mount> - the NFS mount point configured on the HDFS cluster
  • <NameNode> - the IP address or hostname of the NameNode in the HDFS cluster
  • <NameNode Port> - the port on the NameNode in the HDFS cluster
  • <HDFS path> - the path to the HDFS directory from which you plan to copy data
  • <MapR file system path> - the path in the MapR cluster to which you plan to copy HDFS data
To copy data from HDFS to MapR file system using the NFS, complete the following steps:
  1. Mount HDFS.
    Issue the following command to mount the MapR cluster to the HDFS NFS mount point:
    mount <MapR NFS Server>:/<maprfs_nfs_mount> /<hdfs_nfs_mount>
    Example
    mount 10.10.100.175:/mapr /hdfsmount
  2. Copy data.
    1. Issue the following command to copy data from the HDFS cluster to the MapR cluster:
      hadoop distcp hdfs://<NameNode>:<NameNode Port>/<HDFS path> file:///<hdfs_nfs_mount>/<MapR file system path>

      Example

      hadoop distcp hdfs://nn1:8020/user/sara/file.txt file:///hdfsmount/user/sara
    2. Issue the following command from the MapR cluster to verify that the file was copied to the MapR cluster:
      hadoop fs -ls /<MapR file system path>
      Example
      hadoop fs -ls /user/sara