public static boolean isDistributedFileSystem(final FileSystem fs) throws IOException {
    FileSystem fileSystem = fs;
    // If passed an instance of HFileSystem, it fails instanceof DistributedFileSystem.
    // Check its backing fs for dfs-ness.
    if (fs instanceof HFileSystem) {
      fileSystem = ((HFileSystem) fs).getBackingFs();
    }
    return fileSystem instanceof DistributedFileSystem;
  }
Returns True is <code>fs</code> is instance of DistributedFileSystem n
hbase-server/src/main/java/org/apache/hadoop/hbase/util/FSUtils.java