Six bays is where RAID 6 becomes the sensible default: two-drive fault tolerance while keeping four drives of usable capacity — the media-library and prosumer size. Cheapest in stock right now: QNAP TS-664-8G 6-Bay at $896.99.
| Brand | Model | Bays | CPU | RAM | Network | Wty | Price | Buy |
|---|---|---|---|---|---|---|---|---|
| QNAP | TS-664-8G 6-Bay QTS 5 | 6 | Intel Celeron N5105 (4-core) | 8GB DDR4 | 2x 2.5GbE | 2yr | $896.99 | Buy → |
| UGREEN | NASync DXP6800 Plus 6-Bay UGOS Pro | 6 | Intel Core i3-1215U (6-core) | — | — | 2yr | $939.15 | Buy → |
| Asustor | Flashstor 6 Gen2 FS6806X All-Flash ADM | 6 | — | — | 10GbE | 3yr | $1,040.99 | Buy → |
| UGREEN | NASync DXP6800 Pro 6-Bay UGOS Pro | 6 | Intel Core i5-1235U (10-core) | 8GB DDR5 | 2x 10GbE | 2yr | $1,099.99 | Buy → |
| Asustor | Lockerstor 6 Gen3 AS6806T 6-Bay ADM | 6 | AMD Ryzen quad-core 3.8GHz | 16GB DDR5 ECC | 10GbE | 3yr | $1,770.99 | Buy → |
Six bays is the media-library size, and the first configuration where serious fault tolerance stops being expensive. RAID 6 across six drives keeps four drives of usable capacity while surviving two simultaneous failures — and with today's 20TB-class drives stretching rebuilds past a day, that second parity drive is no longer paranoia. The buyers here are running multi-terabyte Plex or Jellyfin libraries, editing photo and video archives, or consolidating a homelab's storage into one chassis with room to breathe.
The in-stock field at six bays is narrower and more interesting than at four: UGREEN's DXP6800 line brings i-series CPUs and dual 10GbE, QNAP's TS-664 extends the reference TS-platform with PCIe expansion, and Asustor fields both the ECC-equipped Lockerstor 6 Gen3 and the all-NVMe Flashstor — the one genuinely silent option in the size. Every price below is live; at this tier the gaps between models are hundreds of dollars and move weekly.
The six-bay tier also carries a decision the smaller sizes never face: spinning, flash, or both. This is the first size where all three exist as real products — conventional drive bays, Asustor's all-NVMe Flashstor, and hybrid layouts using the M.2 slots most of these models ship. The right answer maps to your workload's shape: bulk media wants spindles, active editing wants flash, and most prosumers discover they want a small amount of the second attached to a large amount of the first.
Default to RAID 6: with six 20TB drives that is 80TB usable and any two drives can fail — the configuration that survives the classic disaster of a second drive dying mid-rebuild. RAID 5 at six large drives keeps 100TB usable but leaves the whole array hanging on one parity drive through every day-long rebuild; take that trade only with a rigorous backup and an appetite for re-ripping. The per-terabyte cost difference between the two is exactly one drive, and our NAS Builder computes both live.
Six bays also unlocks useful hybrid layouts: four spinning drives in RAID 6 for the library plus two bays (or the M.2 slots most of these models carry) for a fast working tier. On the Flashstor, the calculus inverts — six NVMe sticks in RAID 5 deliver silent, editing-grade speed, at flash prices our SSD tracker shows live. Whatever the layout, populate from one purchase batch where possible; matched drives with a cold spare on the shelf beat a mixed pool assembled across months of shortage pricing.
Hot-spare policy is worth an explicit decision at six bays: dedicating one bay to a spare converts RAID 6 into a five-drive array that begins rebuilding the instant a member fails, no human required. The cost is one bay of capacity; the benefit is that the two-drive protection window never depends on how quickly you notice an alert while on holiday. Households can reasonably skip it and keep a cold spare on the shelf; anyone whose array carries client work or irreplaceable archives should take the automatic option.
Cheapest in-stock 6-bay (QNAP TS-664-8G 6-Bay, $896.99) plus 6 × MDD 20TB at $309.99 each = $2,756.93 for 80TB usable in RAID 6 — about $34.46 per usable terabyte. Re-run this for any capacity in the NAS Builder.
Model any drive count and RAID level in the RAID planner, and compare drive prices per terabyte on the NAS drive tracker. Upgrading an existing array instead? The upgrade planner nets out the resale value of the drives you retire.
What to weigh at this tier: network first — a six-drive RAID 6 array streams sequential reads far past 2.5GbE, so the dual-10GbE UGREEN units and Asustor's 10GbE boxes are spending money where it shows, while 2.5GbE models bottleneck large transfers. CPU second: transcode-heavy Plex wants the Intel iGPU units; ZFS-curious buyers and business data want Asustor's ECC option. And plan the power budget honestly — six spinning drives idle at a real wattage, which is where the all-flash Flashstor makes its quiet, expensive case.
Budget-wise, expect the drives to run three to five times the enclosure at this tier, which reframes the enclosure decision entirely: the premium for the right six-bay — the 10GbE, the ECC, the iGPU your library needs — amortizes to noise across the build. The expensive mistake at six bays is not overpaying for the enclosure; it is buying the wrong one and discovering the limitation after sixty terabytes of data has made migration a weekend project. Decide the requirements first, then let the live prices pick among qualifying models.
Six-drive arrays are where drive class starts to matter as much as drive price. Enterprise and NAS-Pro drives carry higher sustained-workload ratings and longer warranties than base NAS drives, and in a RAID 6 array that will scrub, rebuild and stream concurrently, those ratings describe real duty. The per-terabyte gap between classes is often smaller than assumed — frequently inverted for recertified enterprise stock — so check the live rankings before defaulting to consumer NAS drives.
Vibration is the quiet variable at six spindles: drives rated for multi-bay enclosures (rotational-vibration sensors are the tell) hold their performance in a full chassis where desktop drives degrade. And plan the spare at purchase time — a seventh drive on the shelf costs one more unit now, versus shortage-market pricing plus shipping days when a member fails. Six-bay owners who skip the spare usually buy it eventually, at the worst possible moment.
The signature 6-bay mistake is RAID 5 across six large drives because the extra usable drive is tempting. The arithmetic that argues against it: a rebuild reads every sector of five surviving drives for a day or more, and the array's survival hangs on zero additional failures and zero unrecoverable read errors for the duration. RAID 6 exists precisely for this window — at six bays its cost is one drive, and our worked example above shows what that drive costs in per-terabyte terms today.
Two further traps: populating gradually with whatever capacity is on sale each month, which strands the array at its smallest member and complicates every future expansion — decide the target capacity once and buy toward it; and pointing a six-drive array at a 2.5GbE network, then wondering why 'the NAS is slow' — the array outruns the wire severalfold, and the 10GbE models in the table above (or a PCIe upgrade on the QNAP) are the actual fix.
A final six-bay-specific trap: forgetting that a bigger array raises the stakes of the enclosure itself failing. Sixty-plus terabytes in one chassis means the backplane, PSU and OS are now single points of failure for a data volume that would take days to restore over any network. The mitigations are boring and effective — keep the config exported, know your OS's array-migration story (most can import a foreign array into a replacement chassis), and hold the irreplaceable subset on a second, smaller box. The array is the library; it should never be the archive of record for anything you cannot re-acquire.
If your library already measures in tens of terabytes or grows by more than a few terabytes a year, yes: six bays lets you run RAID 6 while keeping four drives of usable capacity, and defers the next chassis migration by years. If your data is stable and modest, the 4-bay page's economics serve you better.
RAID 6 as the default: two-drive fault tolerance, four drives usable. With 20TB-class drives, rebuild windows are long enough that single-parity RAID 5 leaves you exposed exactly when the array is working hardest. RAID 5's extra usable drive is only worth it with a strong backup and replaceable content.
Four drives' worth: six 20TB drives yield 80TB usable; six 12TB drives yield 48TB. Two drives go to parity, and any two can fail simultaneously without loss. Our RAID planner models every level and drive size combination.
The Intel-iGPU units: UGREEN's DXP6800 Pro (i5, dual 10GbE) and QNAP's TS-664 both hardware-transcode 4K. Asustor's Ryzen-based Gen3 lacks an iGPU — fine for direct play, wrong for mixed-client transcoding. Live prices for all three are in the table above.
For editing workloads, silence-sensitive rooms, and speed over capacity — yes, and Asustor's Flashstor 6 effectively owns the category. For bulk media storage, no: NVMe per-terabyte pricing remains several times spinning-disk pricing in the current shortage, a gap our SSD tracker shows live.
Enclosure plus six drives, with drives dominating — at today's prices a six-drive 20TB RAID 6 array alone runs well past the cost of any enclosure below. Use the NAS Builder to total your exact configuration at live prices before committing.