Tablo 4 Tuner already has 2 USB ports. How about option for drive migration from port1 to port2 or port2 to port1?
To go further, what about RAID1 to second port to help prevent loss of data when drive crashes?
For devices with single port, accomplish through use of powered hub.
Let used know that Tablo will be unavailable until migrate completes. Then let user choose to keep original drive operating (for archival migrate) or second drive (for migrate upgrade).