Disk array control device with an internal connection system for efficient data transfer

#The present invention relates to control devices of disk array devices for storing data in a plurality of magnetic disk devices.

#In view of the fact that the input/output (I/O) performance or throughput of a disk subsystem (referred to as a “subsystem” hereinafter) is less by approximately three to four orders of magnitude than the I/O throughput of main memories of computers which use semiconductor memory devices as their storage media, attempts have conventionally been made to reduce this difference, namely, to improve the I/O throughput of the subsystem. One prior known approach to improving the subsystem's I/O throughput is to use a system, called a “disk array”, for constituting the subsystem from a plurality of magnetic disk devices, such as fixed or “hard” disk drives (HDDs), which are applicable for use in storing data.

#FIG. 2 shows an arrangement typical of one known type of disk array. This includes a plurality of channel interface (IF) units 411 for execution of data transmission between a mainframe 50 and a disk array controller 2, a plurality of disk IF units 414 for execution of data transfer between HDDs 20 and the disk array control unit 2, a cache memory unit 14 for temporarily storing data of the HDDs 20, and a shared memory unit 15 for storing control information relevant to the disk array controller 2 (for example, information concerning data transfer control between the channel units 411 and disk IF units 414 and the cache memory unit 14), wherein the cache memory unit 14 and shared memory unit 15 are arranged so that they are accessible from all of the channel IF units 411 and disk IF units 414. With this disk array, the channel IF units 411 and disk IF units 414 are connected to the shared memory unit 15 on a one-to-one basis; similarly, the channel IF units 411 and disk IF units 414 are connected one by one to the cache memory unit 14. This connection form is called a star connection.

#FIG. 1 is a block diagram of a disk array controller representing an embodiment of the present invention.

#FIG. 2 is a block diagram of a prior art disk array controller.

#FIG. 3 is a block diagram of another prior art disk array controller.

#Hereunder, the preferred embodiments of the disk array controller of the present invention will be described with reference to the accompanying drawings.

#FIG. 1 is a block diagram of a disk array controller representing an embodiment of the present invention.

#The disk array controller 1 is mainly composed of two channel IF units 411 for connecting two main frames 50; two channel IF units 413 for FCs (Fiber Optic Channels) for connecting two work stations 51; two disk IF units for SCSI 414 for connecting magnetic disk units 20; two disk IF units for FC 415 for connecting magnetic disk units 20; four selector units 13; two cache memory units 14; two shared memory units 15; access paths 0:135; access paths 1:136; and access paths 2:137. In this embodiment, the access paths 0:135 and the access paths 1:136 are assumed to be all equal in bandwidth per line (for example, 200 MB/sec). Hereafter, both of the main frame 50 and the work station 51 may be referred to as host computers for convenience of description.