// Read in the header
//
long startTime = System.currentTimeMillis();
ReadBlockHeader header = new ReadBlockHeader(versionAndOpcode);
header.readFields(in);
int namespaceId = header.getNamespaceId();
long blockId = header.getBlockId();
Block block = new Block( blockId, 0 , header.getGenStamp());
long startOffset = header.getStartOffset();