// no need to flush since we know out is not a buffered stream
FileChannel fileCh = ((FileInputStream)blockIn).getChannel();
LongWritable waitTime = new LongWritable();
LongWritable transferTime = new LongWritable();
sockOut.transferToFully(fileCh, blockInPosition, dataLen,
waitTime, transferTime);
datanode.metrics.addSendDataPacketBlockedOnNetworkNanos(waitTime.get());
datanode.metrics.addSendDataPacketTransferNanos(transferTime.get());
blockInPosition += dataLen;
} else {