Elimination of vertical bus queueing within a hierarchical memory architecture

A system for processing a data access transaction within a hierarchical data storage system, wherein said data access transaction is split between a data access request and a data access response, said system comprising:

• processing means for delivering a data access request from a source device to a plurality of data storage devices within said hierarchical data storage system, wherein said data access request includes a target address and a source path tag, said source path tag including at least one device identification tag that uniquely identifies at least one data storage device within each level of said hierarchical data storage system traversed by said data access request;
• and
• processing means responsive to a data access request hit at a given data storage device among said plurality of data storage devices for delivering a data access response to said source device, wherein said data access response includes said source path tag and said target address.