Storage control unit and storage system

Abstract

A structure of control units and storage units is provided in which, if a port for connecting the storage units fails, any storage unit in a plurality of storage unit groups can be accessed from one control unit. Specifically, a distinctively arranged structure is provided in which dual paths are provided, with each path connected to a plurality of storage unit groups, whereby, in normal operation, dual paths are used as data transfer paths to allow faster access. When a port or path failure occurs, the dual paths allow RAID functions to be maintained.

What is claimed is:  
     
         1 . A data storage system comprising: 
 a group of first storage units;    a group of second storage units;    a plurality of access paths;    each of said first storage units having a connection to a pair of said access paths different from said other first storage units,    each of said second storage units having a connection to a pair of said access paths different from said other second storage units.    
     
     
         2 . The data storage system of  claim 1  wherein said access paths are fiber channels.  
     
     
         3 . The data storage system of  claim 1  wherein said access paths are SCSI paths.  
     
     
         4 . The data storage system of  claim 1  wherein said access paths are exclusive of said first and second storage units.  
     
     
         5 . The data storage system of  claim 1  further comprising: 
 a first storage control unit having a plurality of first connecting ports; and  
 a second control unit having a plurality of second connecting ports,  
 said access paths being connected to at least to one of said first connecting ports or to one of said second connecting ports.  
 
     
     
         6 . The data storage system of  claim 5  wherein said access paths are fiber channels.  
     
     
         7 . The data storage system of  claim 5  wherein said access paths are SCSI paths.  
     
     
         8 . The data storage system of  claim 5  wherein said access paths are exclusive of said first and second storage units.  
     
     
         9 . A data storage system comprising: 
 a group of first storage units;    a group of second storage units;    a plurality of access paths;    each pair of said access paths being in data communication with only one of said first storage units, whereby each first storage unit is connected to a pair of access paths different from said other first storage units,    each pair of said access paths being in data communication with only one of said second storage units, whereby each second storage unit is connected to a pair of access paths different from said other second storage units.    
     
     
         10 . The data storage system of  claim 9  wherein said access paths are fiber channels.  
     
     
         11 . The data storage system of  claim 9  wherein said access paths are SCSI paths.  
     
     
         12 . The data storage system of  claim 9  wherein said access paths are exclusive of said first and second storage units.  
     
     
         13 . The data storage system of  claim 9  further comprising: 
 a first storage control unit having a plurality of first connecting ports; and  
 a second control unit having a plurality of second connecting ports,  
 said access paths being connected to at least to one of said first connecting ports or to one of said second connecting ports.  
 
     
     
         14 . The data storage system of  claim 13  wherein said access paths are fiber channels.  
     
     
         15 . The data storage system of  claim 13  wherein said access paths are SCSI paths.  
     
     
         16 . The data storage system of  claim 13  wherein said access paths are exclusive of said first and second storage units.  
     
     
         17 . A data storage system comprising: 
 a plurality of first means for storing data;    a plurality of second means for storing data;    a plurality of data connection means for transferring data,    each pair of said data communication means being in data communication with only one of said first means;    each pair of said data communication means being in data communication with only one of said second means.    
     
     
         18 . The data storage system of  claim 17  wherein said data connection means are one of fiber channels and SCSI paths.  
     
     
         19 . The data storage system of  claim 17  wherein said data connection means are exclusive of said first and second means  
     
     
         20 . The data storage system of  claim 17  further comprising: 
 a first storage control unit having a plurality of first connecting ports; and  
 a second control unit having a plurality of second connecting ports,  
 said data connection means being connected to at least to one of said first connecting ports or to one of said second connecting ports.