How much storage fits in the TerraMaster F4-425?
By Devin Chua · Data checked by Owen Nakamura · Updated The TerraMaster F4-425 takes 4 drives, up to 120 TB raw, but usable is the number that matters: 4 × 8 TB in TRAID gives 21.83 TiB, and it survives 1 drive failing. The gap from raw capacity is parity, and TRAID lets you grow with mixed drive sizes.
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CMR NAS drives for the F4-425, by price per TB
Only families with confirmed CMR recording and a 24/7 rating, in stock on Amazon.ca and sized for the F4-425. SMR drives are deliberately kept out.
What sets the F4-425 apart
The only alternative to Synology with a genuine SHR counterpart: TRAID uses mixed drive sizes, TRAID+ matches SHR-2 with double fault tolerance. If you have a stack of mismatched drives, you lose less here than with UGREEN or QNAP.
Who the F4-425 is for
The F4-425's Intel N5095 (4 cores, 2.0 GHz) is the home-NAS sweet spot. Its integrated graphics hardware-transcode Plex — 4K HEVC included, through Intel Quick Sync — and it runs a stack of Docker containers without complaint; heavy virtualization is the one thing it leaves to bigger machines. With 4 GB stock and up to 16 GB, the F4-425 suits a household that wants its media server and its drives in one quiet box.
How the F4-425's network shapes the drive choice
The F4-425 runs 1 × 2.5GbE. Two-and-a-half gigabit is about 280 MB/s — almost exactly what a modern high-capacity NAS drive reads off its outer tracks — so the F4-425 sits in the sweet spot where an ordinary CMR drive saturates the link and a Pro model buys nothing on speed. Drives under about 8 TB fall short here for lack of areal density; from 8 TB up, a standard IronWolf or WD Red Plus is the right call on the F4-425.
A worked configuration for the F4-425
Seagate IronWolf Pro or WD Red Plus in every bay is the recommendation for the F4-425. At 4 × 8 TB in TRAID, the F4-425 lands 21.83 TiB usable, gives up 8 TB to parity, and survives 1 drive failing. Step the same 4 bays of the F4-425 up to 16 TB drives and it holds roughly twice that, at the CA$/TB the live table above shows.
TRAID or RAID 6 in the F4-425?
With 4 bays the F4-425 gives a real choice. In TRAID it keeps 21.83 TiB of the 4 × 8 TB and survives one failure; RAID 6 spends one more drive for two. The trade tips with large drives: after a failure the F4-425 must read every surviving drive in full to rebuild, which on 20 TB drives runs the better part of a day under peak load. So from 16 TB per drive up, RAID 6 is the calmer choice in the F4-425.
One rule holds on every NAS, the F4-425 included: use CMR drives, not SMR. SMR drives rewrite overlapping tracks and collapse during a RAID rebuild, dragging a repair from hours into days.
The TerraMaster drive policy on the F4-425
unrestrictedOpen, and TerraMaster advertises it: “TerraMaster restricts neither drive brands nor third-party SSDs.” The compatibility list is purely advisory.
The F4-425 at a glance
| Bays | 4 × 3.5-inch SATA and 2.5-inch SATA SSD |
|---|---|
| Maximum raw capacity | 120 TB 4 × 30 TB, per the manufacturer |
| Processor | Intel N5095 (4 cores, 2.0 GHz) |
| Memory | 4 GB, DDR4 SO-DIMM, no ECC (1 slot) 16 GB official |
| M.2 NVMe | none No M.2 slots. Note: NVMe, DDR5 and 5GbE only come with the F4-425 Plus, not this model. |
| Network | 1 × 2.5GbE |
| Operating system | TOS 6 |
| RAID types | TRAID, TRAID+, Single, JBOD, RAID 0, RAID 1, RAID 5, RAID 6, RAID 10 TRAID also makes use of mixed drive sizes. |
Keep calculating
To see how much capacity is left after parity, the F4-425 capacity calculator is preset to its 4 bays and RAID types. For the F4-425, the wider basics of choosing a drive are in the buying guides, where we also explain why CMR rather than SMR is mandatory in any RAID array.
Frequently asked questions
What is the maximum storage in the F4-425?
4 drives, up to 120 TB raw per the manufacturer. 4 × 30 TB, per the manufacturer
How much of the F4-425 is actually usable?
In the F4-425, 4 × 8 TB in TRAID yields about 21.83 TiB — that is 24 TB in drive-maker terms, with 8 TB to parity. It shows less than the label because it counts in powers of two.
Can I fit larger drives in the F4-425 later?
Yes, and with TRAID it is easy: swap the F4-425's drives for larger ones one at a time, and the gain arrives once the second-largest drive is also larger.
Can I put third-party drives in the F4-425?
Yes. TerraMaster locks no drive brand on the F4-425 — its compatibility list is guidance, not a gate — so any CMR NAS drive works.
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)