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Black 16-bay rackmount NAS unit with front drive trays and rear dual power supplies

Synology Inc.

Synology Inc. RS4021xs+ 16-bay rackmount NAS 16GB DDR4

SKU CH-KTFG-FAM0Z MPN RS4021xs+

A 16-bay rackmount NAS with an 8-core 2.1 GHz Intel Xeon D-1541 processor, 16 GB DDR4 ECC memory, dual 10GbE and four 1GbE ports, supporting up to 288 TB raw capacity and expansion to 40 bays

  • CPUIntel Xeon D-1541 8-core (16-thread) 2.1 GHz
  • Form factor16-Bay
  • Power draw145.79 W (Access) 62.68 W (HDD Hibernation)
  • LAN ports2 × 10GbE + 4 × 1GbE
  • USB ports2 x USB 3.2 Gen 1
  • Drive interface16 x SATA (16 x Bay)

Model RS4021xs+

  • Handles massive workloads with 234698 random read IOPS
  • 16 drive bays expandable to 40 for growing storage needs
  • Dual 10GbE ports deliver high-speed network connectivity
  • Intel Xeon 8-core processor powers demanding multi-user services
  • 16GB ECC DDR4 memory scales to 64GB for reliability

16-bay rackmount NAS for data-intensive workloads

The RS4021xs+ is a 16-bay rackmount NAS powered by an Intel Xeon D-1541 8-core processor running at 2.1 GHz. It ships with 16 GB of DDR4 ECC memory expandable to 64 GB across four slots. The unit is designed for environments that require high throughput and compute capacity for many simultaneous users.

Sustained throughput with redundant power

Under continuous load the system delivers up to 234,698 4K random read IOPS and 6,258 MB/s sequential read performance. Dual redundant power supplies protect against a single PSU failure or accidental cord removal. Hot-swappable fans can be replaced without powering down the chassis, keeping services available during maintenance.

Sixteen drive bays with expansion headroom

Sixteen SATA bays accept drives from the Synology compatibility list; only Synology SAT5200 2.5" or SNV3500 series SSDs may be used for SSD cache. Two PCIe slots allow additional network or storage cards. An RX1217RP or RX1217 expansion unit can increase the total bay count to 40. The operating temperature range is 0 °C to 35 °C.

How it compares

Measured against everything we stock in Rack-Mounted NAS Servers, at today’s prices. Recalculated every night.

Price $4,488.99
Cheaper than about 72% of the 763 comparable items (median $6,564.99).

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Specifications

Product
Brand nameSynology
Model nameRS4021xs+
Recommended useUltra high prerformance for large number of users
Processor
CPUIntel Xeon D-1541 8-core (16-thread) 2.1 GHz
Memory
Installed RAM16 GB DDR4
Maximum RAM capacity64 GB
RAM slots4
Storage
Drive interface16 x SATA (16 x Bay)
Drives includedDiskless System
Supported RAID modes0, 1, 5, 6, 10, JBOD, Synology RAID F1, Basic
Connectivity
Protocol supportSMB, AFP, NFS, FTP, WebDAV, CalDAV, iSCSI, Telnet, SSH, SNMP, VPN (PPTP, OpenVPN, L2TP)
Ports & slots
LAN ports2 × 10GbE + 4 × 1GbE
USB ports2 x USB 3.2 Gen 1
Power
Power draw145.79 W (Access)
62.68 W (HDD Hibernation)
Power details100 V to 240 V AC, 50/60 Hz, single phase
Size & build
Form factor16-Bay
Product dimensions5.21 in × 18.98 in × 25.85 in
Product weight38.36 lb (17.4 kg)
Shipping weight22.97 kg
Package size889 × 635 × 298 mm
In the box
In the box1 x RS4021xs+ main unit
1 x Quick Installation Guide
1 x Accessory pack
2 x AC power cords
Environment & compliance
Temperature rangeOperating temperature: 0 °C to 35 °C (32 °F to 95 °F)
Storage temperature: -20 °C to 60 °C (-5 °F to 140 °F)
Humidity range5% to 95% RH
More details
Maximum capacity288 TB

Other versions of this model

4 more in the same range

Questions about this item

How much power does the RS4021xs+ draw when the drives are active versus when they are hibernating?

The unit consumes 145.79 W during access and drops to 62.68 W when the hard drives enter hibernation.

Which drive models are officially supported for storage pools and SSD cache on this unit?

Only drives on the Synology compatibility list may form storage pools; SSD cache requires Synology SAT5200 2.5" or SNV3500 series SSDs.

Can the RS4021xs+ be expanded with an RX1217RP expansion unit that I already own?

Yes, the RS4021xs+ supports up to 40 bays when connected to an RX1217RP or RX1217 expansion unit.

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