Veja o que encontrei no blogue Construindo o Windows 8 :
Q) How do I replace a working drive with a bigger one (or just cycle drives)? Does it require a “rebuild”?
As long as you have created mirrored or parity spaces, you can always simply remove a physical disk within the pool, and add a different (perhaps larger) one. Within a short period of time, the impacted spaces will automatically be resynchronized (the Storage Spaces design optimizes this operation to be faster than traditional RAID rebuilds). You can determine whether all spaces are healthy – i.e. data has been resynchronized so as to maintain the designated number of copies –either via Control Panel or via PowerShell commands.
Virtualizando o armazenamento para escala, resiliência e eficiência
Então, meu entendimento é apenas puxar o drive, substituir e deixar que ele faça o que é necessário.