I ran a hadoop job and when I look in some map tasks I see they are not running where the file's blocks are. E.g., the map task runs on slave1, but the file blocks (all of them) are in slave2. The files are all gzip.
Why is that happening and how to resolve?
UPDATE: note there are many pending tasks, so this is not a case of a node being idle and therefore hosting tasks that read from other nodes.