3 Key Upgrades in the TerraMaster F4-423 Over the F4-421
Two M.2 NVMe slots The F4-423 adds two M.2 NVMe slots that can be used for caching or as dedicated storage, a feature missing from the F4-421.
Four SATA bays unchanged The four SATA bays still accept any mix of 3.5-inch and 2.5-inch drives, keeping the same flexible storage options as its predecessor.
NVMe and SATA can coexist You can now run an NVMe storage pool alongside your SATA array, making this a meaningful generational step for mixed-speed workflows.