I am currently using storage spaces on Windows Server 2012 R2. 2 disks (2*3TB) are installed with one virtual volume set to two-way mirroring. Since this is a very small server, it only has one SATA port left. For increasing the storage capacity, I am thinking about adding 1 more drive, but this time with a capacity of 6TB. According to Mixing disks of different sizes in a Storage Spaces pool , one might think that a possible way would be to 1. remove one of the 3TB drives, 2. add the new 6TB drive, 3. rebuild the storage space, 4. format the old 3TB drive and then 5. add it again to the pool. Would I then be able to access 6TB of capacity and still have two-way mirroring resiliency? Can't find any documents that cover this scenario.
I figured it out myself using a virtual machine and several virtual disks. The mentioned procedure does work indeed and you can use the whole capacity while maintaining resiliency (I have written data to the whole virtual disk). Of course the order of the steps is important, and cleaning the old drive before readding it to the pool.