Best 4-Bay NAS 2026 — The Sweet-Spot Buying Guide
Four bays is the home-NAS sweet spot: in RAID 5 or SHR you get roughly (n-1) drives of usable space (4×8TB ≈ 24TB usable), single-drive fault tolerance with an escape hatch to two-drive redundancy (RAID 6 / SHR-2), and one-at-a-time capacity upgrades. The pick splits on one fork: for data-integrity/prosumer buyers it's the Synology DS923+ (ECC, 32GB RAM ceiling, 10GbE path — but no iGPU); for media-server buyers it's the QNAP TS-464 (iGPU transcoding, dual 2.5GbE, PCIe slot). The TerraMaster F4-424 is the raw hardware-value pick, the Asustor AS5404T the NVMe-flexibility pick (four M.2 slots), and the UGREEN DXP4800 the newcomer-value pick. Whatever you buy: CMR drives only, and RAID is not a backup.
The one thing to know: RAID is not a backup. RAID (except RAID 0) protects against DRIVE failure — if one disk dies, the array keeps running while you replace it. It does nothing against the things that actually destroy data: accidental deletion, ransomware, file corruption, a failed controller, theft, fire, or a power surge that takes the whole box. All of those hit the live array and every mirror of it at once. RAID is about uptime and availability; a backup is a separate, ideally offline or off-site copy you can restore from. You need both, and 'I have RAID' is the single most common — and most dangerous — misconception in home storage.
The best 4-bay NAS, ranked
Research-based picks (how we evaluate) built from manufacturer specifications and storage engineering — no prices, no star ratings, qualitative tier bands only, and an honest drawback on every box. Every enclosure ships empty; the drives row at the end covers the other half of the purchase.
Synology DiskStation DS923+
Tier band: Prosumer / upper-mid tier (enclosure only)
4 bays · AMD Ryzen R1600 dual-core · 4GB DDR4 ECC (expandable to 32GB ECC) · 2× 1GbE, optional 10GbE add-in card · 2× M.2 NVMe (2280) · ECC memory · DSM · expandable with DX517 unit
A genuine small-business/prosumer box: ECC memory (rare at this size), RAM expandable to 32GB, an optional 10GbE upgrade path, and DSM's Btrfs snapshots and backup suite — built to grow with you.
Best for: Self-hosters and prosumers who want ECC, real RAM headroom, and a 10GbE upgrade path under DSM
Watch out: The Ryzen R1600 has NO integrated GPU, so it is a poor choice for Plex/Emby hardware transcoding — plan on direct-play or a separate transcoding box. It ships with only 1GbE, and Synology's own-branded-drive push is felt most on this Plus line: NVMe storage pools and some HDD features officially expect Synology drives, so check the compatibility list carefully.
Check price on AmazonQNAP TS-464
Tier band: Mid tier (enclosure only)
4 bays · Intel Celeron N5095 quad-core · 4GB DDR4 (expandable to 16GB) · 2× 2.5GbE · 2× M.2 PCIe Gen3 NVMe · PCIe Gen3 expansion slot · HDMI 4K · QTS/QuTS hero · hardware transcoding
The flexible 4-bay tinkerer's box: dual 2.5GbE, two NVMe slots, and a rare PCIe slot you can populate with a 10GbE card or extra M.2 carrier as your needs grow.
Best for: Power users and self-hosters who want an upgrade path (10GbE via PCIe) on an affordable 4-bay
Watch out: Same QNAP security caveat as the TS-264 — never expose it directly to the internet, and patch it. The 4GB base RAM is modest for heavy container/VM use, so budget for a RAM upgrade if you plan to run many apps.
Check price on AmazonTerraMaster F4-424
Tier band: Value / mid tier (enclosure only)
4 bays · Intel N95 quad-core · 8GB DDR5 (expandable to 32GB) · 2× 2.5GbE · TOS 6 operating system · also supports third-party OS (TrueNAS / Unraid) · hardware transcoding
The most raw hardware per dollar here — a current N95 CPU, 8GB of DDR5 expandable to 32GB, and dual 2.5GbE — and TerraMaster openly documents installing TrueNAS or Unraid if you outgrow its own OS.
Best for: Budget-conscious buyers who value hardware specs and the option to run a third-party NAS OS
Watch out: TerraMaster's own TOS software is less mature and less polished than Synology DSM, with a smaller app catalog, and the brand has had past security-hardening criticism — keep it off the open internet. Its main appeal for many buyers is as capable hardware to run TrueNAS/Unraid on, not the bundled OS.
Check price on AmazonAsustor AS5404T (Nimbustor 4 Gen2)
Tier band: Mid tier (enclosure only)
4 bays · Intel Celeron N5105 quad-core · 4GB DDR4 (expandable to 16GB) · 2× 2.5GbE · four M.2 NVMe slots (usable as storage or cache) · HDMI · ADM operating system · hardware transcoding
Its standout is four M.2 NVMe slots — enough to build a genuine all-flash NVMe pool or generous cache alongside the four HDD bays, which is unusual at this size and price.
Best for: Users who want to mix hard-drive capacity with a fast NVMe pool, or maximize flash flexibility
Watch out: Asustor's ADM operating system and app ecosystem are smaller and less widely documented than Synology's or QNAP's, so you'll lean more on community guides. Base RAM is only 4GB, and the M.2 slots share PCIe lanes — check current documentation for full-population performance behavior.
Check price on AmazonUGREEN NASync DXP4800
Tier band: Mid tier (enclosure only)
4 bays (+2 M.2) · Intel N100 quad-core · 8GB DDR5 (expandable to 16GB) · 2× 2.5GbE · 2× M.2 NVMe · HDMI · UGOS Pro · also runs third-party OS · hardware transcoding
A 4-bay take on the same value formula — N100, DDR5, dual 2.5GbE, plus two NVMe slots and extra bays for a capacity-plus-flash build, at an aggressive price for the hardware.
Best for: Buyers who want a modern, well-priced 4-bay and are comfortable with a newer software ecosystem (or plan to run TrueNAS)
Watch out: Same newness caveat as the DXP2800: UGOS Pro is young and its long-term support/security history is still being written, so weigh that against the hardware value — and consider TrueNAS if you want a proven, community-supported OS on it.
Check price on AmazonThe Drives NAS Hard Drives — WD Red Plus / Seagate IronWolf (CMR)
Tier band: Priced per drive by capacity (bought separately from the enclosure)
3.5" NAS-rated hard drives · CMR (conventional) recording — NOT SMR · rated for 24×7 operation and multi-drive vibration · NASware / AgileArray firmware · common home capacities run through the mid-double-digit-TB range
Every NAS above ships as an empty enclosure — the drives are the other half of the purchase. NAS-rated CMR drives (WD Red Plus, Seagate IronWolf) are built for 24×7 duty, vibration in multi-bay chassis, and RAID rebuilds, which desktop drives are not.
Best for: Anyone buying a NAS enclosure who needs reliable, rebuild-safe drives to populate it
Watch out: Avoid SMR (shingled) drives in a NAS RAID array — SMR's slow re-write behavior can make RAID rebuilds crawl or fail. The plain WD Red (non-Plus) and many cheap desktop/external-shucked drives are SMR; confirm CMR on the spec sheet. Buy from a source with a clear return path in case of early failure, and always run a NAS with a real backup — RAID is not a backup.
Check price on AmazonWhy is a 4-bay NAS the sweet spot?
The 4-bay case rests on arithmetic, not marketing. RAID redundancy has a fixed cost in drives, and four bays is where that cost stops hurting:
- Usable capacity: (n-1) instead of (n/2). A 2-bay mirror gives up half its raw space to redundancy. A 4-bay in RAID 5 or single-redundancy SHR gives up only one drive: 4×8TB ≈ 24TB usable, 4×12TB ≈ 36TB — three times the usable space of a 2-bay mirror built from the same drives, for one extra drive's worth of redundancy overhead.
- One-at-a-time upgrades. With four bays you can grow capacity by replacing drives individually as budget allows (especially flexible under SHR, which uses mixed sizes efficiently — SHR vs classic RAID), or start with two or three drives and add more later. A full 2-bay has no such path except replacing both drives.
- Single-drive tolerance with an escape hatch. RAID 5/SHR survives one drive failure. If the array grows large and a second failure during a rebuild starts to worry you, four bays lets you step up to RAID 6 / SHR-2 (two-drive redundancy) — an option a 2-bay simply doesn't have. More on sizing in how many bays do you need.
Beyond four bays, diminishing returns set in for most homes: 6- and 8-bay boxes cost more, draw more power, and mostly serve buyers who already know they need them.
Media server or data integrity? The fork that decides your 4-bay pick
Almost every 4-bay decision reduces to one honest either/or, because no box in this class gives you both:
- Media-server buyers want an iGPU. Plex/Jellyfin hardware transcoding needs an integrated GPU, and the Intel N-series/Celeron boxes — QNAP TS-464, TerraMaster F4-424, Asustor AS5404T, UGREEN DXP4800 — all have one. They also ship dual 2.5GbE, which the Synology doesn't.
- Data-integrity/prosumer buyers want ECC. Only the Synology DS923+ offers ECC memory (expandable to 32GB ECC), an optional 10GbE card, and DSM's Btrfs snapshot and backup suite — but its Ryzen R1600 has no integrated GPU, so it's a poor transcoding box: plan on direct-play or a separate transcoding machine.
Be honest about which buyer you are. If the NAS's main job is serving video to TVs and phones, buy the iGPU and skip ECC (ECC is nice, not mandatory — a tested backup protects your data far more). If the main job is irreplaceable data plus Docker/VM self-hosting headroom, the DS923+'s ECC and 32GB ceiling are the real prosumer features (Docker/VM capability by CPU class).
4-bay spec comparison — the specs that matter
From our master spec data. Note the fork in the iGPU and ECC rows: the DS923+ is the only ECC box and the only one without hardware transcoding.
| Feature | Synology DS923+ | QNAP TS-464 | TerraMaster F4-424 | Asustor AS5404T | UGREEN DXP4800 |
|---|---|---|---|---|---|
| CPU class | Ryzen R1600 (x86, no iGPU) | Celeron N5095 (x86) | Intel N95 (x86) | Celeron N5105 (x86) | Intel N100 (x86) |
| RAM base → max | 4GB → 32GB | 4GB → 16GB | 8GB → 32GB | 4GB → 16GB | 8GB → 16GB |
| Networking | 1GbE (+10GbE opt.) | 2× 2.5GbE | 2× 2.5GbE | 2× 2.5GbE | 2× 2.5GbE |
| NVMe slots | 2× M.2 | 2× M.2 (+PCIe) | Varies by rev. | 4× M.2 | 2× M.2 |
| ECC | Yes (ECC) | No | No | No | No |
| OS | DSM | QTS / QuTS | TOS / TrueNAS | ADM | UGOS / TrueNAS |
| iGPU / transcoding | No (no iGPU — poor for transcoding) | Yes (Intel iGPU, hardware transcoding) | Yes (Intel iGPU, hardware transcoding) | Yes (Intel iGPU, hardware transcoding) | Yes (Intel iGPU, hardware transcoding) |
Don't forget the drives: CMR only, and a rebuild is the stress test
NAS-rated drives use CMR (conventional magnetic recording); many cheap desktop and external drives use SMR (shingled), which overlaps tracks to pack in more capacity but must rewrite whole zones on write, making sustained and random writes slow. In a NAS this matters most during a RAID rebuild: an SMR drive can slow a rebuild to a crawl or cause it to drop out of the array, risking a second failure before it finishes. Use CMR NAS drives (WD Red Plus, Seagate IronWolf) in an array; the plain WD Red was infamously SMR. Always confirm CMR on the spec sheet.
This matters more on a 4-bay than a 2-bay: a four-drive RAID 5 rebuild reads every surviving drive end-to-end while writing the replacement, and an SMR drive in that array is exactly how rebuilds crawl or fail. Stick to WD Red Plus or Seagate IronWolf class CMR drives and confirm CMR on the spec sheet — full CMR vs SMR explainer.
Frequently Asked Questions
If you can afford the enclosure and the extra drives, usually yes. In RAID 5 or SHR a 4-bay gives you roughly (n-1) drives of usable space — with 4×8TB that's about 24TB usable versus 8TB from a 2-bay mirror using comparable drives — plus the option of two-drive redundancy (RAID 6 / SHR-2) and one-at-a-time capacity upgrades. A 2-bay mirror 'costs' half its raw space to redundancy; a 4-bay RAID 5 costs only a quarter. If your needs are just photos and backups, a 2-bay is still plenty.
One with an Intel integrated GPU: the QNAP TS-464, TerraMaster F4-424, Asustor AS5404T, and UGREEN DXP4800 all have Intel chips with hardware transcoding. The Synology DS923+ is the exception — its AMD Ryzen R1600 has NO integrated GPU, so it's a poor choice for hardware transcoding; plan on direct-play or a separate transcoding box if you buy it. If media serving is the primary job, buy the iGPU.
No — ECC is nice, not mandatory. The 'ZFS requires ECC or it eats your data' claim is a myth; non-ECC boxes protect data for millions of users, and a tested backup protects your data far more than ECC does. Among these five, only the Synology DS923+ offers ECC (4GB base, expandable to 32GB ECC), which is why it's the prosumer/data-integrity pick. Treat ECC as a bonus, not a checkbox.
In RAID 5 or single-redundancy SHR, roughly the total of all drives minus one: 4×8TB ≈ 24TB usable, 4×12TB ≈ 36TB usable. RAID 6 / SHR-2 (two-drive redundancy) subtracts two drives: 4×8TB ≈ 16TB usable. RAID 10 halves raw capacity. These are approximations before filesystem overhead — and remember RAID redundancy is availability, not a backup.
NAS-rated CMR drives — WD Red Plus or Seagate IronWolf. Avoid SMR (shingled) drives in any RAID array: SMR's slow rewrite behavior can make a rebuild crawl or drop the drive from the array, and a 4-drive rebuild is exactly when you can't afford that. The plain WD Red (non-Plus) and many cheap desktop or shucked drives are SMR — confirm CMR on the spec sheet. Every enclosure here ships empty; the drives are the other half of the purchase.
It protects against one drive failing while the array stays online — nothing more. It does nothing against accidental deletion, ransomware, corruption, theft, or fire, which hit the live array all at once. On larger arrays a second drive can fail during the stressful rebuild, which is why some owners choose RAID 6 / SHR-2. Either way, RAID is not a backup: keep a separate 3-2-1 backup (3 copies, 2 media types, 1 off-site) and test a restore.
How we work
We're a research-based site: we analyze manufacturer specifications, storage and filesystem engineering, and aggregated owner-feedback themes rather than lab-testing every enclosure. We explain tradeoffs plainly, always name a downside, and report measurable specs — never a guarantee about data safety. RAID is not a backup, drives fail, and only a tested 3-2-1 backup protects your data. Read our full methodology →