1. An apparatus for input/output (I/O) target selection within a data storage system having clustered nodes of initiators, I/O targets, and grouped storage logical units, the apparatus comprising: a state definition component configured to define access states for each combination of one or more combinations, each combination including a node of a plurality of the initiators, an I/O target to which the initiators of the node are able to write data, and a storage logical unit associated with the I/O target, each access state defining a readiness of the combination to perform I/O; a profiler component configured to produce an access state profile for each I/O target; a rank criteria compiler configured to compile rank criteria as a basis for best-fit identification of I/O targets for a logical unit (LU) group; a best-fit identifier configured to, responsive to the profile component and the rank criteria compiler identify a ranked best-fit order of I/O targets for an LU group; and, a target selector configured to select an I/O target for an LU group from the ranked best-fit order, the selected I/O target balancing a maximization of continuing existing I/O service availability of the LU group, a maximization of a post target failover I/O service availability of the LU group, a maximization of post target failover I/O service reliability of the I/O group, and a minimization of performance impact of target failover of the I/O group.