Importance

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Abstract

A disk drive array controller generally has a host I/O port configured for connection to a host computer and a plurality of disk I/O ports configured for connection to a corresponding plurality of disks forming a disk drive array. A controller constructed in accordance with various aspects of the present invention may include a host I/O processor in communication with the host I/O port and configured to perform I/O transactions with the host computer through the host I/O port; a cache memory; a front end caching subsystem in communication with the host I/O processor and configured to cache blocks of data comprising host I/O transactions in the cache memory; a disk array I/O processor configured to access host data in the cache memory and in communication with the plurality of disk drives, the disk array I/O processor processing host I/O transactions into disk I/O transactions; and a back end caching subsystem in communication with the disk array I/O processor, the back end caching subsystem configured to cache disk array meta-data in the cache memory. Variations of this basic system are possible, and contemplated as within the scope of the present invention. The disk drive array controller may further include a communication path between the front end caching subsystem and the back end caching subsystem, whereby allocation of blocks in the caching subsystems are synchronized. The communication path may be, for example, a control store common to the front end caching subsystem and the back end caching subsystem, the control store holding a data structure through which caching and I/O transaction information are communicated between the front end caching subsystem and the back end caching subsystem.

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First Claim