Patent ID: 6757753
Filing Date: 2004-06-29
Classification: G06F

Abstract:
A method for handling access to data storage in a storage system in which a storage array contains data in a logical volume on behalf of a server, the server sends access requests through a plurality of input/output (I/O) devices to a plurality of array controllers that control access to the storage array and the logical volume, the logical volume is under the control of only one array controller at a time, control of the logical volume can switch between the array controllers, comprising the steps of:forming an access request at the server for access to the logical volume wherein the request includes a global identifier comprising a logical unit number of the logical volume to which the request is directed; selecting a first data transfer path from the server to one of the I/O devices, independently of the array controller that has control over the logical volume identified by the logical unit number in the request; sending the access request through the selected first data transfer path to the one I/O device; determining a selected one of the array controllers that is to receive the access request, independently of the selected first data transfer path from the server to the one I/O device, wherein the determination is performed based in part on the logical unit number in the request; selecting a second data transfer path from the one of the I/O devices to one or more of the array controllers through a second network fabric comprising a plurality of available paths within the storage system connecting the I/O devices and the array controllers; and sending the access request from the one I/O device to the selected array controller via the second data transfer path instructing the selected array controller to respond to the access request.