Patent ID: 7814293

Claim:
A method for performing host-side IO rerouting in a storage virtualization subsystem (SVS) comprising a plurality of redundant storage virtualization controllers (SVCs) including a first SVC and a second SVC, and a physical storage device (PSD) array connected thereto including at least one PSD, the method comprising: providing at least one logical media unit (LMU) including sections of said PSD array, said at least one LMU including a first LMU that is assigned to only one of said SVCs at the same time; receiving, by said first SVC, a host IO request addressing said first LMU; determining whether said first SVC that receives the host IO request addressing said first LMU is an LMU owner of said first LMU; and rerouting, when said first SVC and said second SVC are on-line, said host IO request to said second SVC that is determined to be the LMU owner of said first LMU when said first SVC is determined not to be the LMU owner of said first LMU; and wherein said rerouting step comprises the steps of: the first SVC forwarding the host IO request to the second SVC over an inter-controller communications (ICC) channel; the second SVC requesting first data from the first SVC if the host IO request requires that the first data be transferred from a host; the host IO request being executed by the second SVC; the second SVC forwarding second data to be transferred to the host to the first SVC if the host IO request requires that the second data be transferred to the host; the first SVC forwarding the second data to the host; and on the host IO request completion, completion status of the host IO request being forwarded to the first SVC by the second SVC and then forwarded to a host by the first SVC.