Wise ordering for writes-combining spatial and temporal locality in write caches for multi-rank storage

摘要

A storage system has a storage controller for an array of storage disks, the array being ordered in an sequence of write groups. A write cache is shared by the disks. The storage controller temporarily stores write groups in the write cache responsive to write groups being written to their respective arrays. The write groups are assigned to a global queue ordered by ages. The controller selects a quantity of write groups for attempted destaging to the arrays responsive to a predetermined high threshold for the global queue and to sizes and the ages of the write groups in the global queue, and allocates the selected quantity among the arrays responsive to quantities of certain ones of the write groups in the global queue. Write groups are destaged to respective arrays responsive to the selected allocation quantity for the array and the sequences of the write groups in the arrays.