MRAsyncDiskService fails when it's given local dirs it can't create or write. Per
MAPREDUCE-1213 this conflicts with the previous behavior. The TTs will no longer start on hosts where the config has localdirs that can not be created (ie if some hosts don't have the same local mounts).
The TT and JT should prune out invalid local dirs (ones that fail checkLocalDirs ie that it can not create) before giving them to MRAsyncDiskService and using them otherwise.
Also mapred-default.xml states that mapred.local.dir that do not exist are ignored, this should be updated as directories that don't exist are created (if possible), they're only ignored if they can not be created.