private FileChecksum getFileChecksum(final FileSystem fs, final Path path) {
      try {
        return fs.getFileChecksum(path);
      } catch (IOException e) {
        LOG.warn("Unable to get checksum for file=" + path, e);
        return null;
      }
    }
Try to open the "source" file. Throws an IOException if the communication with the inputFs
fail or if the file is not found.
hbase-mapreduce/src/main/java/org/apache/hadoop/hbase/snapshot/ExportSnapshot.java