Patent ID: 6684209
Filing Date: 2004-01-27
Classification: G06F,H04L,Y10S

Abstract:
A method for controlling access to a logical unit in a computer storage subsystem having a storage controller and a storage unit, said storage controller being configured to control data requests to the storage unit, said storage unit including a port and a plurality of storage areas that are configured to store data, said storage unit being provided apart from said storage controller, said method comprising:creating at said computer storage subsystem a first mapping, said first mapping being among a logical unit identifier, a virtual unit identifier and a uniquely assigned host identifier, the logical unit identifier identifying a logical unit that corresponds to a physical storage area in the computer storage subsystem, the virtual unit identifier defining a storage area in the storage unit and being associated with the logical unit identifier; storing information on said first mapping in a first mapping table, said first mapping table including a plurality of logical unit identifiers, a plurality of virtual unit identifiers, and a plurality of uniquely assigned host identifiers, one or more said plurality of virtual unit identifiers being not necessarily unique; creating at said computer storage subsystem a second mapping, said second mapping being between a dynamically assigned host identifier and said uniquely assigned host identifier; receiving at said computer storage subsystem an inquiry request for at least one virtual logical unit in said computer storage subsystem, said request comprising at least a dynamically assigned host identifier and a requested virtual unit identifier, said dynamically assigned host identifier corresponding to an issuer of said inquiry request and said requested virtual unit identifier corresponding to said at least one virtual logical unit; searching said second mapping using said dynamically assigned host identifier to obtain a corresponding uniquely assigned host identifier; searching said first mapping using said corresponding uniquely assigned host identifier; determining whether access by said issuer of said inquiry request, to a logical unit corresponding to said requested virtual unit identifier, is permissible based upon whether a relation between said corresponding uniquely assigned host identifier and said requested virtual unit identifier exists in said first mapping; if said access is permissible, then establishing accessibility between said logical unit corresponding to said requested virtual unit identifier and said issuer, said logical unit determined from a relation between said requested virtual unit identifier and a corresponding logical unit identifier determined from said first mapping; and reporting whether said access is permissible to said issuer of said inquiry request.