System and method for managing data in a cache system for a disk array

摘要

A cache system is described which is adapted for staging data between host memory and a disk array comprising a plurality of disk storage devices plus associated controller unit, data being storable across the disks of the array in the form of strides, each stride comprising a multi-sector 'stripe' of data on each of two or more devices of the array and an associated multi-sector parity block on a further array device. The cache system includes means for linking the data and associated parity making up a stride within the cache as a cache data unit which is manipulated in the cache as a single entity. References from the host to data held within the cache causes the referenced cache unit to move to the head of a list of cache units. Using such a cache system, when a cache unit at the bottom of the list is committed to disk, there is an increased likelihood that most or all the data making up a stride will be in the cache and therefore the number of redundant accesses to the disk needed to generate parity data will be reduced or eliminated.