DSM 7.3 third-party drive policy; verify exact MPN
DS225+ + 2 × 4TB IronWolf
A checked starting combination targeting about 4TB usable with shr / raid 1-style single-drive redundancy.
Lowest checked total$621.17Amazon + Amazon
Lowest one-store total$621.17Amazon
Approx. usable4TB
Checked value$155.29/TB
What the bundle contains
Capacity and redundancy
The mirror can continue after one drive fails; keep a second copy of originals outside the NAS.
Approximation: $(2 - 1) × 4TB = 4TB$. Filesystem formatting, system partitions, snapshots, and RAID implementation reduce displayed free space.