Disk control device and storage device using it

A storage device comprising:

• at least two clusters, each including a disk control device having a plurality of channel controllers that send and receive commands and data to and from an upper system, a plurality of disk controllers that control disk units, and a cache that temporarily store data between the upper system and the disk units;
• and
• apparatus for connecting said at least two clusters to each other, said apparatus comprises:
• at least two first buses, which are physically independent from each other, included in a first cluster, said at least two first buses are connected to said channel controller, said disk controller and said cache of said first cluster,
• at least two second buses, which are physically independent from each other, included in a second cluster, said at least two second buses are connected to said channel controllers, said disk controllers and said cache of said second cluster, and
• a cache which is connected to said at least two first buses of said first cluster and said at least two second buses of said second cluster, and in which a specified set of data is commonly accessible from each of said channel controllers or said disk controllers.

An apparatus for use in a storage device having at least two clusters, each including a disk control device having a plurality of channel controllers that send and receive commands and data to and from an upper system, and a plurality of disk controllers that control disk units, said apparatus comprising:

• a first bus included in a first cluster, said first bus is connected to said channel controller, and said disk controller of said first cluster;
• a second bus included in a second cluster, said second bus is connected to said channel controllers, and said disk controllers of said second cluster;
• and
• a common resource which is connected to said first bus of said first cluster and said second bus of said second cluster, and in which a specified set of data is commonly accessible from each of said channel controllers or said disk controllers of said clusters.