I was investigating issue in Sqoop project(http://sqoop.apache.org/). Problem is that we are reporting number of written filesystem bytes back to the user and on Hadoop 0.23/2.x we're always getting 0. I've noticed that there was some refactorization in FileSystem counter related code and found
MAPREDUCE-3542 requesting backward compatibility.
Included patch seems to be adding counter "FileSystemCounter":
But it appears that original name is "FileSystemCounters" (Notice the plural "s" at the end of name):
I therefore believe that this counter should be renamed in order to provide backward compatibility. I might fix this discrepancy in Sqoop, but I believe that other projects/users might also be affected and therefore it would be better to fix it in upstream.