Patent ID: 8392753

Claim:
A method of handling a failure during a data migration process which is constructed and arranged to migrate data from a storage device of a source array to a storage device of a target array, each storage device being capable of operating in (i) an active mode in which that storage device is permitted to perform read and write operations and (ii) a passive mode in which that storage device is not permitted to perform read and write operations, the method comprising: while a host initially accesses host data from the storage device of the source array using multipath I/O software, providing an active-to-passive command to the source array, the active-to-passive command directing the source array to transition the storage device of the source array from the active mode to the passive mode; when the storage device of the source array transitions from the active mode to the passive mode, transitioning the storage device of the target array from the passive mode to the active mode and beginning a data transfer operation which transfers data from the storage device of the source array to the storage device of the target array; in response to modification commands sent to the target array from the host while the data transfer operation is ongoing, processing the modification commands by modifying host data on the target array and on the source array; and in response to detection of a failure event in which the target array loses communication with the source array for a predefined amount of time, transitioning the storage device of the target array from the active mode back to the passive mode.