A technique provides transitioning from an original device to a new device within a data storage array. The technique involves initiating a copying activity within the data storage array, the copying activity copying data from the original device to the new device. The technique further involves, while the data is being copied from the original device to the new device, routing write requests that target logical storage which is currently supported by the original device to both the original device and the new device. The technique further involves, after the data has been copied from the original device to the new device, performing a configuration change which routes I/O requests that target the logical storage to the new device rather than the original device.