Seems like you use SDD that creates vpath devices from the hdisks. The hdisks appear as often as there are paths, i.e. if you see every hdisk four times there are four paths from your server's FC adapter to the storage box. To make the best use of the multi path I/O you need to use the vpath devices for creating/extending a vg and must not use the hdisk devices. Basic SDD commands are hd2vp (to create vpath devices from hdisks) vp2hd (to remove the vpath device) and dpovgfix (if the vpath configuration got messed up).