You cannot start a FlashCopy mapping or consistency group when the FlashCopy mapping or consistency group is in the stopping state. If you want to start a FlashCopy mapping or consistency group, the FlashCopy mapping or consistency group must be in the Prepared state.
Wait until the FlashCopy mapping or consistency group reaches the Stopped or idle_or_copied state and then prepare the FlashCopy mapping or consistency group before starting it.