/* Write the header */
BlockChecksumHeader blockChecksumHeader = new BlockChecksumHeader(
dataTransferVersion, namespaceId, block.getBlockId(),
block.getGenerationStamp());
blockChecksumHeader.writeVersionAndOpCode(out);
blockChecksumHeader.write(out);
out.flush();
final short reply = in.readShort();
if (reply != DataTransferProtocol.OP_STATUS_SUCCESS) {