Benchmarks: CrystalDiskMark
Going by the specification sheet, TerraMaster's F2-221 goes head-to-head with the Qnap TS-251B. Both are capable of saturating the Gigabit interface, but in the more demanding 4KQ32 test, the Qnap has a slight advantage.
The initial performance numbers are healthy, but for those with Plex on the mind, our experience of the Celeron J3355 is that while the chip is officially capable of 4K transcoding, the end result can be a mixed bag, and users with dreams of transcoding to multiple clients simultaneously ought to be considering something more powerful.
