Just a heads up that you can get details of the men of the 21st Battalion Canadian Expeditionary Force at Al Lloyd's fascinating website at http://21stbatallion.ca/ He has collected hundreds of photos of the men, their gravemarkers (GWGC and others) and a long list of biographies. There are also lots of photos and history of the battalion itself.
Also, Library and Archives Canada have published on line a number of the Service records in pdf format. It seems that if they get a request for a copy of the service record, they take that opportunity to scan the file to pdf.
Sarge