A hardware configuration and methodology for serializing or partially serializing WRITE requests directed to a unified data set are subsequently distributed to one or more remote arrays containing a corresponding mirror unified data set. For each unified data set, one of the local disk arrays over which the unified data set is distributed is selected as a supervisor disk array, and a unified sequence number component is included within that supervisor disk array. WRITE requests generated by a local array to mirror unified data set data to a mirror unified data set must be associated with a unified sequence number, and the WRITE requests are therefore serialized or partially serialized by the unified sequence number component. Additional direct communications links are provided between the local arrays over which a unified data set is distributed both to facilitate WRITE-request serialization and to provide a redundant communications paths for added reliability.