private void readHeader() throws IOException {
try {
// process the file header
Bufferlo fileHeader = new Bufferlo();
fileHeader.readFromChannel(persistentMap.getFileChannel(), 8);
fileHeader.consume("GLAZED\n\n");
} catch(ParseException e) {
// the file header is broken, bail
throw new IOException("The file cannot be read because it is not of the expected type");
}