If the DoM component extent_end is set larger than the MDT dom_stripesize (via lfs setstripe -Eextent_end -L mdt ) then this currently generates an error. Since users do not have any easy way to determine the dom_stripesize on the MDT, and it may in fact be different on a per-MDT basis (e.g. if MDT0000 sets dom_stripesize=0 because it was formatted before DoM, or it is adjusted automatically by the MDS when the MDT is nearly full). This complicates DoM usage for users (imagine a striped directory that has different DoM size limits for the MDTs it is striped over).
The MDS should automatically adjust the component extent_end to match the MDT dom_stripesize, and if dom_stripesize=0 then the DoM component should be removed.