TerraMaster F2-425: capacity calculator
By Devin Chua · Data checked by Owen Nakamura · Updated In the TerraMaster F2-425 with 2 × 8 TB in TRAID you keep 7.28 TiB usable (8 TB in drive-maker terms), surviving 1 drive failing. The calculator below is preset to the 2 bays and the RAID types TOS 6 actually offers on this model (including TRAID, which uses mixed drive sizes), with the cost to fill in Canadian dollars from live Amazon.ca prices.
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Preset for the F2-425: 2 bays, and only the RAID types this model actually supports.
SHR (Synology Hybrid RAID)
That is 8 TB the way drive makers label capacity. Your NAS shows you the smaller number because it counts in powers of two.
Drives: from CA$1,008 for 2 × 8 TB (CA$63.01/TB overall)
What to know about the F2-425
The cheapest x86 two-bay with 2.5-gigabit networking. With two equal-size drives TRAID gives no advantage over RAID 1; it only gets interesting once you add a larger drive later.
The F2-425 at a glance
| Bays | 2 × 3.5-inch SATA and 2.5-inch SATA SSD |
|---|---|
| Maximum raw capacity | 60 TB 2 × 30 TB, per the manufacturer |
| Processor | Intel N5095 (4 cores, 2.0 GHz) |
| Memory | 4 GB stock, DDR4 SO-DIMM, no ECC (1 slot) 16 GB official |
| M.2 NVMe | none No M.2 slots. NVMe and 5GbE come only with the F2-425 Plus. |
| Network | 1 × 2.5GbE |
| RAID types | TRAID, TRAID+, Single, JBOD, RAID 0, RAID 1 |
| Third-party drives | unrestricted Open. TerraMaster explicitly does not restrict drive brands. |
TRAID: TerraMaster's answer to SHR on the F2-425
TRAID computes like SHR — only the largest drive comes off the total — so the F2-425uses mixed drive sizes instead of leveling to the smallest. TRAID+ matches SHR-2 and survives two simultaneous failures. That makes TerraMaster, alongside Synology, the only maker in this price band with a genuine flexible RAID; UGREEN and QNAP offer nothing like it.
Two bays means RAID 1 in practice on the F2-425
With two drives there is no sensible alternative to RAID 1 on the F2-425 (or TRAID with two drives, which is arithmetically the same). You pay half your capacity for fault tolerance: 2 × 8 TB becomes 8 TB, not 16. RAID 5 needs at least three drives and is not available here. For more capacity per dollar without giving up safety, a four-bay model is the move.
Which drives belong in the F2-425?
CMR NAS drives rated for 24/7 use — Seagate IronWolf, WD Red Plus, Toshiba N300 or their Pro variants. Our drive picks for the F2-425 with live prices show which of those currently offers the best capacity per dollar. If you are working back from a target capacity instead, the drive-count calculator works out how many drives you need.
Frequently asked questions
How much storage is left in the F2-425 with 2 × 8 TB?
About 7.28 TiB usable — 8 TB in drive-maker terms — computed in TRAID, the sensible default for this model. It survives 1 drive failing. The gap from the 16 TB raw goes to parity.
Which RAID types does the F2-425 support?
TOS 6 offers TRAID, TRAID+, Single, JBOD, RAID 0, RAID 1 on the F2-425. TRAID is the one that matters: it lets the F2-425 use mixed drive sizes instead of leveling every drive down to the smallest.
Can I put third-party drives in the F2-425?
Open. TerraMaster explicitly does not restrict drive brands.
How much memory does the F2-425 take?
It ships with 4 GB (DDR4 SO-DIMM, no ECC (1 slot)). 16 GB official There is one slot.
Why does my NAS show less than the calculator says?
Because the maker and the OS count differently. A drive maker calls one trillion bytes a TB; the NAS counts in powers of two and calls that a TiB — about 9 percent less. That is why this calculator leads with the TiB figure: it is the number you will read off the screen.
Devin Chua works out which drives, RAM and NVMe cache fit which NAS model at nasdrives.ca, and what the RAID choice means for usable capacity, checked against what is in stock on Amazon.ca.
Data checked by Owen Nakamura, Technical editor (data checking)