Patent ID: 6839773

Claim:
A program for responding to an input-output request from a host to effect a transfer to a specified location within a logical volume in a disk array storage device wherein a host operating system utilizes a first, uniquely identified base unit control block corresponding to the logical volume to effect a transfer in response to the input-output request, said program enabling the host to send overlapped input-output requests to the logical volume and comprising: A) a host parallel access application operable within the host including: i) a first host module for defining at least one related, uniquely identified unit control block that identifies the logical volume including the establishment of a parallel access control block for each unit control block associated with the logical volume and a parallel access main control block for the logical volume through which each of the base and related unit control blocks can be identified, and ii) a second host module for interrupting the operating system response to the input-output request including a process that assigns one of the base and related unit control blocks to the input-output request, and a process that returns control of the response to the input-output request to the operating system identifying the assigned unit control block whereby the host operating system can issue overlapped input-output requests to the given logical volume, and B) a plurality of facility modules operable within the disk array storage facility including: i) a first facility module that establishes a table for the logical volume with entry input-output requests and corresponding parameters, and ii) a second facility module that tests the parameters for each new input-output request to the logical volume with respect to the parameters for input-output request entries in the table to determine which, of a plurality of control functions including enabling the processing of the input-output request by the storage facility, will be performed.