The best NAS for 20TB-class drives depends on bay count: a 4-bay such as the Synology DiskStation DS925+ or QNAP TS-464 suits most homes, while an 8-bay such as the Synology DS1825+ or QNAP TS-873A gives room to grow. Four 20TB drives in RAID 5 provide about 60 TB of usable space, and the NAS must be rated for large volumes and CMR drives. Check the maker’s drive compatibility list before buying, because policies on third-party drives have changed.
Our top picks
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Quick comparison of NAS picks for 20TB drives
| Pick | Best for | Bays | Network | Raw capacity with 20TB drives | Price range |
|---|---|---|---|---|---|
| Synology DiskStation DS925+ | Best overall 4-bay | 4 | Dual 2.5GbE | 80 TB | Mid to upper |
| QNAP TS-464 | 4-bay with PCIe and media features | 4 | Dual 2.5GbE | 80 TB | Mid |
| Synology DiskStation DS1525+ | 5-bay growth | 5 | 2.5GbE | 100 TB | Upper-mid |
| Synology DiskStation DS1825+ | 8-bay value | 8 | 2.5GbE | 160 TB | Upper-mid to premium |
| QNAP TS-873A | 8-bay for power users | 8 | 2.5GbE class | 160 TB | Premium |
| Synology DiskStation DS1823xs+ | 10GbE business use | 8 | Onboard 10GbE | 160 TB | Premium |
Port speeds and memory differ by revision. Verify the current spec sheet before ordering.
How much usable space 20TB drives give
| Configuration | Drives | RAID level | Usable space | Drive failures tolerated |
|---|---|---|---|---|
| 2-bay mirror | 2 x 20TB | RAID 1 | 20 TB | 1 |
| 4-bay | 4 x 20TB | RAID 5 | 60 TB | 1 |
| 4-bay | 4 x 20TB | RAID 6 | 40 TB | 2 |
| 5-bay | 5 x 20TB | RAID 5 | 80 TB | 1 |
| 8-bay | 8 x 20TB | RAID 6 | 120 TB | 2 |
These figures are decimal terabytes, and the file system reports slightly less. With a 20TB drive, a rebuild after a failure can take a day or more, so many people choose RAID 6 or a second copy of the data rather than RAID 5 alone.
Best overall 4-bay: Synology DiskStation DS925+
The DS925+ is a four-bay model with dual 2.5GbE ports, and it runs Synology’s DSM software with Synology Photos, Drive and Hyper Backup. Four 20TB drives give 80 TB raw. Synology’s drive policy for Plus models changed in 2025, so confirm the latest firmware and compatibility list for third-party drives. The trade-off is that Synology’s hardware is modest for the price, and it focuses on software.
Best 4-bay for features: QNAP TS-464
QNAP’s TS-464 is a four-bay model with dual 2.5GbE, a PCIe slot for expansion and strong media features. It suits Plex users and buyers who like the flexibility of QNAP’s QTS or QuTS hero systems. The drawback is a more complex interface and a history of security patching that you need to keep up with.
Best 5-bay growth option: Synology DiskStation DS1525+
The DS1525+ adds a fifth bay, giving 100 TB raw with 20TB drives and 80 TB usable in RAID 5. It is a sensible step if you expect to outgrow four bays but do not need eight. Its network is 2.5GbE, so it is not a 10GbE machine.
Best 8-bay value: Synology DiskStation DS1825+
The DS1825+ gives eight bays and is a common choice for a small business or a heavy home user. Eight 20TB drives mean 160 TB raw. Synology volumes above about 108 TB have required more RAM according to reviewers, so check the memory limit for the model.
Best 8-bay for power users: QNAP TS-873A
The TS-873A is an eight-bay unit that suits virtualisation and heavy multi-user work. It is more expensive and complex than the Synology alternative. It is a good fit if you want flexibility and expansion cards.
Best for 10GbE: Synology DiskStation DS1823xs+
The DS1823xs+ has eight bays, onboard 10GbE and support for ECC memory. It is a premium business machine. Reviewers note its price is far above home models, so it is only worth it if 10GbE and a five-year warranty matter.
Which 20TB drives to use
Use CMR NAS drives, not SMR desktop drives. The Seagate IronWolf Pro 20TB is a 7200 RPM CMR drive with a five-year warranty and a data recovery service plan according to Seagate’s datasheet. The WD Red Pro and Toshiba N300 Pro are also CMR drives at 7200 RPM with five-year warranties. Mixed brands work, but matching drives keeps behaviour even. Buying drives in different batches reduces the chance that they fail together.
How to choose a NAS for 20TB drives
- Plan the bays: Choose the bay count you need for two years of growth.
- Check volume limits: Large volumes can need more RAM.
- Look at the network: 2.5GbE is fine for a hard-drive NAS. 10GbE needs SSD cache or many drives.
- Plan backups: RAID is not a backup. Keep a second copy on another device or in the cloud.
- Consider noise and power: Large 7200 RPM drives are louder and run warmer than low-speed drives.
Frequently Asked Questions
How many 20TB drives do I need for a NAS?
Two is the minimum for redundancy, and four gives a good balance. Four drives in RAID 5 give about 60 TB usable. More drives increase capacity and also the number of parts that can fail.
Is RAID 5 safe with 20TB drives?
It tolerates one drive failure, but rebuilds take a long time and a second failure during that window loses data. RAID 6 or a separate backup is safer.
Will any NAS accept 20TB drives?
Most current NAS devices do, but older models may not. Check the maker’s compatibility list and the maximum volume size.
Do I need 10GbE for a 20TB NAS?
Not usually. A 2.5GbE link carries about 280 MB/s, which matches a few hard drives. 10GbE helps with SSD arrays or heavy multi-user work.
Can I recover data from a failed NAS?
Often yes if the drives are healthy, since RAID sets can be rebuilt by recovery software or a service. Stop using the NAS after a failure and avoid reinitialising drives.
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