16-bay 3U enterprise rackmount NAS
Synology RackStation RS4021xs+ 16-Bay Enterprise Rackmount NAS
The Synology RackStation RS4021xs+ is a 16-bay 3U enterprise storage server with an 8-core Intel Xeon processor, 16 GB ECC memory, built-in dual 10GbE and redundant power for demanding multi-user data environments.
- Processor
- Intel Xeon D-1541
- Memory
- 16 GB DDR4 ECC UDIMM
- Drive bays
- 16 / up to 40 (RX1217 × 2)
- Networking
- 4 × 1GbE RJ-45 plus 2 × 10GbE RJ-45
Scale high-throughput business storage from 16 to 40 drive bays
The RS4021xs+ combines a high-density 3U chassis with built-in 10GbE, dual PCIe expansion slots and redundant power. It is designed for data-intensive file services, backup repositories, virtualisation storage and other business workloads that need substantial capacity and connectivity headroom.
Sixteen internal bays
Build a high-capacity SATA storage platform with compatible 3.5-inch HDDs or 2.5-inch SSDs.
Scale to 40 bays
Two RX1217 expansion units can extend the system to a verified maximum of 40 drive bays.
Eight-core Xeon platform
The Intel Xeon D-1541 provides 8 cores and 16 threads for demanding concurrent services.
Built-in 10GbE
Two 10GbE and four 1GbE RJ-45 ports provide immediate high-bandwidth and management-network options.
Dual PCIe expansion
Two full-link Gen3 x8 slots support compatible networking or cache-adapter configurations.
Redundant power design
Dual power supplies help reduce exposure to a single PSU or power-cord interruption.
Who is the Synology RS4021xs+ best for?
A strong choice for
- Enterprise file services and large shared datasets
- High-capacity backup and recovery repositories
- Virtualisation storage with built-in 10GbE
- Organisations expanding from 16 to 40 bays
- Rack deployments requiring redundant power
Consider another model if you need
- A compact short-depth rack system
- Fewer than 16 internal drive bays
- Lower-power branch-office storage
- A dual-controller architecture within one chassis
Key specifications
- Model
- RS4021xs+
- Product type
- 16-bay 3U enterprise rackmount NAS
- Processor
- Intel Xeon D-1541, 8 cores, 16 threads
- CPU frequency
- 2.1 GHz base / 2.7 GHz turbo
- System memory
- 16 GB DDR4 ECC UDIMM
- Maximum memory
- 64 GB (16 GB × 4)
- Drive bays
- 16; up to 40 (RX1217 × 2)
- Drive types
- 16 × 3.5-inch SATA HDD or 2.5-inch SATA SSD
- Networking
- 4 × 1GbE RJ-45 plus 2 × 10GbE RJ-45
- PCIe expansion
- 2 × Gen3 x8 slots (x8 link)
- Dimensions (H × W × D)
- 132.3 × 482 × 656.5 mm
- Warranty
- 5 years
Full technical specifications
Processor and memory
| Model | RS4021xs+ |
|---|---|
| CPU model | Intel Xeon D-1541 |
| CPU quantity | 1 |
| CPU cores and threads | 8 cores, 16 threads |
| CPU architecture | 64-bit |
| CPU frequency | 2.1 GHz base / 2.7 GHz turbo |
| Hardware encryption engine | Supported |
| System memory | 16 GB DDR4 ECC UDIMM |
| Pre-installed memory | 16 GB (16 GB × 1) |
| Total memory slots | 4 |
| Maximum memory capacity | 64 GB (16 GB × 4) |
| Memory guidance | Use Synology memory modules and follow the exact-model manual for supported configurations |
Storage, network and expansion
| Drive bays | 16 |
|---|---|
| Maximum drive bays with expansion | 40 (RX1217 × 2) |
| Compatible drive types | 16 × 3.5-inch SATA HDD or 2.5-inch SATA SSD |
| Hot-swappable front drives | Supported |
| Network ports | 4 × 1GbE RJ-45 plus 2 × 10GbE RJ-45 |
| USB ports | 2 × USB 3.2 Gen 1 |
| Expansion connection | 2 × Infiniband |
| PCIe expansion | 2 × Gen3 x8 slots (x8 link) |
| Drive compatibility | Use only drives listed for the exact system on Synology’s current compatibility list |
Physical design and power
| Form factor | 3U |
|---|---|
| Size (H × W × D) | 132.3 × 482 × 656.5 mm |
| Weight | 17.4 kg |
| Rack installation | 4-post 19-inch rack; RKS-02 rail kit sold separately |
| System fans | 80 × 80 mm × 3 |
| Fan modes | Full-speed, cool and quiet |
| Noise level | 44.7 dB(A) |
| Power recovery | Supported |
| Power supply unit | 800 W or 550 W depending on hardware revision |
| Redundant power supply | Yes |
| AC input | 100 V to 240 V AC |
| Power frequency | 50/60 Hz, single phase |
| Power consumption | 145.79 W (access); 62.68 W (HDD hibernation) |
| British Thermal Unit | 497.14 BTU/hr (access); 213.74 BTU/hr (HDD hibernation) |
Environment, warranty and package
| Operating temperature | 0°C to 35°C |
|---|---|
| Storage temperature | -20°C to 60°C |
| Operating humidity | 8% to 80% RH |
| Storage humidity | 5% to 95% RH |
| Certifications | FCC, CE, BSMI, VCCI, RCM, EAC, CCC, KC, BIS, UL |
| Environment | RoHS compliant |
| Warranty | 5 years |
| Package contents | Main unit × 1; accessory pack × 1; AC power cord × 2; quick installation guide × 1 |
Frequently asked questions about the Synology RS4021xs+
What is the Synology RS4021xs+?
The Synology RS4021xs+ is a 16-bay 3U enterprise rackmount NAS designed for centralised file storage, backup and data management through Synology DSM.
Which processor is in the RS4021xs+?
It uses the Intel Xeon D-1541 with 8 cores, 16 threads, operating at 2.1 GHz base / 2.7 GHz turbo.
How much memory does the RS4021xs+ include?
It includes 16 GB DDR4 ECC UDIMM and supports a verified maximum of 64 GB (16 GB × 4).
How many drive bays does the RS4021xs+ have?
It provides 16 and supports up to 40 (RX1217 × 2).
Which drives are supported by the RS4021xs+?
The verified drive categories are 16 × 3.5-inch SATA HDD or 2.5-inch SATA SSD. Confirm the exact drive model on Synology's current compatibility list before purchase.
What network ports are built into the RS4021xs+?
The RS4021xs+ includes 4 × 1GbE RJ-45 plus 2 × 10GbE RJ-45.
What expansion is available for the RS4021xs+?
It provides 2 × Gen3 x8 slots (x8 link) plus 2 × Infiniband. Use only options listed for the exact model.
Does the RS4021xs+ have redundant power?
Yes. The RS4021xs+ includes redundant power supplies.
What are the dimensions of the RS4021xs+?
It measures 132.3 × 482 × 656.5 mm in height × width × depth and weighs 17.4 kg.
What warranty applies to the RS4021xs+?
Synology specifies 5 years. Warranty coverage starts from the purchase date shown on the receipt, and extension availability varies by region.
- This product is supplied diskless unless the listing explicitly states otherwise; storage drives are sold separately.
- Confirm drives, memory, expansion units, rail kits and add-in cards on Synology’s current compatibility list for the exact model before purchase.
- Actual storage capacity and performance depend on the installed drives, RAID or storage configuration, network and workload.
- The power supply is 800 W on specified T2R hardware revisions and 550 W on specified ULR/VR4 revisions; check the unit serial number and Synology Product Change Notice.
