For DNE filesystems where there are large numbers of remote entries, for example once LU-4684 is landed to restripe directories, or DNE2 striped directories with many renames, the size of the REMOTE_PARENT_DIR may become very large.
In order to limit contention and scaling issues in REMOTE_PARENT_DIR it makes sense to have multiple such directories. As a starting point, one REMOTE_PARENT_DIR_MDTxxxx for each remote MDT would be useful, but it may be necessary to have a tree of directories similar to the O/<seq>/dN object directories. Having a separate REMOTE_PARENT_DIR_MDTxxxx per MDT would also allow LFSCK to efficiently scan remote entries for a given MDT, if there was a problem (e.g. MDT was marked offline and returned into the namespace later).