mdt.mdt_mds_mds_conns is inter-MDT connection counter, and it's used by DNE Commit-on-Sharing and directory auto-split, but it's only counted in mdt_obd_connect(), however upon MDT stop and start, the connection is handled in mdt_obd_reconnect(), as a result, this counter is not accurate, and cause Commit-on-Sharing and directory auto-split fail to work.