Toggling between a first storage configuration and a second storage
configuration includes disabling asynchronous data transfer to a third
storage group from one of the first storage group and the second storage
group and enabling asynchronous data transfer to the third storage group
from an other one of the first storage group and second storage group.
Toggling between a first storage configuration and a second storage
configuration may also include, prior to disabling asynchronous data
transfer to the third storage group, transferring pending data to the
third storage group. Toggling between a first storage configuration and a
second storage configuration may also include, after enabling
asynchronous data transfer to the third storage group, transferring data
to the third storage group that had been pending prior to disabling
asynchronous data transfer to the third storage group.