code: @Override
  	protected void writeDataBlock(byte[] data, int offset, int len, int blockHandle) throws DataStoreException
      {
      	byte[] blockData = new byte[blockSize];
      	System.arraycopy(data, offset, blockData, 0, len);
      	
      	dirtyBlockTable.markDirty(blockHandle, blockData);    	
      	journal.writeDataBlock(blockHandle, (long)blockHandle*blockSize, blockData);
      }
docs: /*
  (non-Javadoc)
  @see net.timewalker.ffmq4.storage.data.impl.AbstractBlockBasedDataStore#writeDataBlock(byte[], int, int, int)