What you are attempting to do is quite common, let me try to explain it further. Ill try to create a video describing this as well.  Today you have a distributed virtual volume A, which is comprised of devices B at site 1 and C at site 2. At some point the array that B is on needs to go away and you need to move B to a new array. Bring in a new array and create lun B1 that is of the same size as B and present it to vplex and claim it. You then do an extent/device mobility job from B to B1, this whole time the virtual volume A is still seen by the host. The synchronization from B to B1 is happening in the background. Any new writes to A are going to B,B1, and C.  At some point you commit the mobility job at which point now the distributed volume A is now comprised of B1 at site 1 and C at site 2.  make sense?
Hello,  Today we have a VPLEX Metro setup between arrays at two different sites.  We are looking into the need to upgrade those arrays.  Considering that VPLEX mobility/migration is not supported between distributed devices, how do we go about migrating from the current arrays to the new arrays using VPLEX?  Thanks,  Will
Migrating Distributed Volumes Between Arrays