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RackStation RS4021xs+

Enterprise NAS with built-in service continuity engineered for data-intensive applications.

Securing your business assets

The 16-bay RS4021xs+ provides solid data security and lightening-fast performance with over 234K 4K random read IOPS and 6,258 MB/s sequential read throughput1. Together with its 8-core processor, ECC memory, advanced snapshot technology, and built-in 10GbE connectivity, the RS4021xs+ can support large multi-user environments while handling data-intensive workloads.

Download Datasheet

Compute

Compute

Intel® Xeon® D-1541 8-core 2.1 GHz

Networking

Networking

Built-in dual-port 10GbE

Memory

Memory

16 GB ECC DDR4 Up to 64 GB

Scalability

Scalability

Up to 40 drive bays with RX1217(RP)

Engineered for service continuity

The RS4021xs+ ensures mission-critical data is always available, enabling businesses to deliver the best results, even in the face of disaster.

Redundant power

Dual PSUs provide protection against a PSU failure or accidental cord removal while hot-swappable fans can be replaced without powering down the system.

Maximize service availability

Synology High Availability (SHA) pairs two identical units together creating an active-passive cluster with minute-level failover. Learn more

Next-generation file system

Btrfs prevents data corruption and reduces maintenance overheads with advanced storage technologies and optimized snapshots. Learn more

Engineered for service continuity

Customize to your business

The RS4021xs+ includes two PCIe slots for performance, networking, and storage upgrades enabling it to adapt to any business environment2.

Double bandwidth
SSD cache<sup>3</sup>
Storage expansion

The ultimate backup solutions — license-free

Hyper Backup

A comprehensive backup and recovery solution for securing data stored on Synology servers. Backup data locally, to another Synology device, rsync server, or cloud-based storage such as Google Drive, Dropbox, S3-compatible destinations, and Synology C2. Deduplication4, integrity checks, and incremental transfer technology reduce bandwidth and storage used. Learn more

Snapshot Replication

Easily schedule flexible point-in-time backups of shared folders and iSCSI LUNs with an RPO as low as 5 minutes and recovery in seconds. Set up replication and failover to other Synology storage systems for fast RTOs and minimal service disruption. Learn more

Keep disaster at bay

Active Backup Suite

Enables administrators to easily backup the entire IT infrastructure to their NAS, including Windows & Linux workstations and servers, file servers, VMware and Hyper-V virtual machines, and Microsoft 365 and Google Workspace accounts. Backups benefit from deduplication, multiversioning, and optimizations to reduce bandwidth and storage used. Learn more

Backup your entire IT infrastructure

Storage for virtualization

Synology iSCSI storage supports mainstream virtualization solutions with an easy management interface to enhance usability. VMware vSphere 6.5 and VAAI integration helps offload storage operations. Windows Offloaded Data Transfer (ODX) speeds up data transfer. OpenStack Cinder support turns your Synology NAS into a block-based storage component. Additionally, Synology Storage Console enables even more simplified storage provisioning and management options in VMware and Windows environments. Learn more

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windows2022
citrix
openstack

All-in-one surveillance solution

Synology Surveillance Station transforms the RS4021xs+ into a feature-packed Network Video Recorder solution. Support for up to 90 IP cameras5 and video analytics such as motion detection, no idle zone, foreign object detection, and anomaly detection cater to the most common surveillance scenarios. Learn more

Secure and private

AES-256 encryption keeps locally-stored footage secure.

Access from anywhere, anytime

Access recordings and live streams whenever you want using a web browser, desktop client, or the DS cam mobile app.

Real-time alerts

Email, SMS, or push notifications alert you when incidents occur or predefined conditions are met.

All-in-one surveillance solution

Works best with Synology drives

Engineered to handle intensive 24/7 workloads, Synology drives consistently deliver top-grade performance.

Enterprise Series 3.5" SATA
Enterprise Series 2.5" SATAEnterprise Series M.2 NVMe
img enterprise-hatimg enterprise-satimg enterprise-snv3500

Powered by Synology DiskStation Manager

The RS4021xs+ runs Synology DiskStation Manager (DSM), the web-based operating system equipped with powerful applications and services for business.

Central Management System

Central Management System

Conveniently manage your fleet of Synology NAS from a centralized console.

Learn more

Synology Drive

Synology Drive

Instantly access your NAS files across multiple devices whenever you want, wherever you are.

Learn more

Collaboration Suite

Collaboration Suite

Satisfy all team collaboration needs behind the safety of your own private cloud with Synology Office, Calendar, and Chat.

Learn more

Virtual Machine Manager

Virtual Machine Manager

Run various operating systems in isolated sandboxes. Seamlessly clone, store, and migrate virtual machines.

Learn more

Security

Security

Shield your Synology NAS from the most sophisticated threats with industry-leading security solutions.

Learn more

Public Cloud Integration

Public Cloud Integration

Back up and synchronize data easily between public cloud accounts and your NAS.

Learn more

5-year warranty

5-year warranty

At Synology, we are committed to product innovation and quality. The RS4021xs+ is backed by a 5-year limited warranty that includes technical support and hardware replacement services to maximize your return on investment. Learn more

RackStation RS4021xs+

product RS4021xsplus front view photo
product RS4021xsplus back view photo
  • 1Power button and indicator
  • 2Alert Off Button
  • 3Drive tray
  • 4Drive status indicator
  • 5PSU fan
  • 6Power Port
  • 7PSU Indicators & Alert Off Buttons
  • 8Console port
  • 91GbE/10GbE RJ-45 Ports
  • 10USB 3.2 Ports
  • 11Expansion port
  • 12PCIe expansion slot
  • 13Reset button
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Notes:

  1. Performance testing conducted by Synology with 10GbE NICs installed. Actual results may vary depending on system configuration, testing methods, and other environmental variables. Check the performance page for additional details.
  2. Network adapter cards, expansion units, other PCIe add-in cards, and storage drives are sold separately. Refer to the compatibility list for compatible devices.
  3. SSD cache can be enabled by using compatible 2.5" SSDs or without occupying drive bays by installing Synology SNV3500 M.2 22110 NVMe SSDs using M2D20 or E10M20-T1 adapter cards, sold separately.
  4. Users have reported total data size reductions of more than 50% when backing up multiple systems with deduplication technology.
  5. Surveillance Station includes 2 free licenses. Connecting more cameras and devices requires additional licenses.
Hardware Specifications
CPU
CPU
 CPU Model Intel Xeon D-1541
CPU Quantity 1
CPU Architecture 64-bit
CPU Frequency 8-core 2.1 (base) / 2.7 (turbo) GHz
Hardware Encryption Engine
Memory
Memory
 System Memory 16 GB DDR4 ECC UDIMM
Memory Module Pre-installed 16 GB (16 GB x 1)
Total Memory Slots 4
Maximum Memory Capacity 64 GB (16 GB x 4)
Notes
  • Synology reserves the right to replace memory modules with the same or higher frequency based on supplier's product life cycle status. Rest assured that the compatibility and stability have been strictly verified with the same benchmark to ensure identical performance.
  • Please select Synology memory modules for optimum compatibility and reliability. Synology will not provide complete product warranty or technical support if non-Synology memory modules are used for memory expansion.
  • For more information about the recommended memory configurations, please check the Hardware Installation Guide of your Synology product.
Storage
Storage
 Drive Bays 16
Maximum Drive Bays with Expansion Unit 40 (RX1217/RX1217RP x 2)
Compatible Drive Type* (See all supported drives)
  • 3.5" SATA HDD
  • 2.5" SATA SSD
Hot Swappable Drive*
Notes
  • Synology only guarantees full functionality, reliability, and performance for Synology drives listed on the compatibility list. The use of non-validated components may limit certain functionality and result in data loss and system instability.
  • "Compatible drive type" indicates drives that have been tested to be compatible with Synology products. This term does not indicate the maximum connection speed of each drive bay.
External Ports
External Ports
 RJ-45 1GbE LAN Port 4 (with Link Aggregation / Failover support)
RJ-45 10GbE LAN Port 2 (with Link Aggregation / Failover support)
USB 3.2 Gen 1 Port* 2
Expansion Port 2
Notes The USB 3.0 standard was renamed to USB 3.2 Gen 1 by the USB Implementers Forum (USB-IF) in 2019.
PCIe
PCIe
 PCIe Expansion 2 x Gen3 x8 slots (x8 link)
Appearance
Appearance
 Form Factor (RU) 3U
Size (Height x Width x Depth) 132.3 mm x 482 mm x 656.5 mm
Weight 17.4 kg
Rack Installation Support* 4-post 19" rack (Synology Rail Kit - RKS-02)
Notes The rail kit is sold separately
Others
Others
 System Fan 80 mm x 80 mm x 3 pcs
Fan Speed Mode
  • Full-Speed Mode
  • Cool Mode
  • Quiet Mode
Easy Replacement System Fan
Power Recovery
Noise Level* 44.7 dB(A)
Scheduled Power On / Off
Wake on LAN / WAN
Power Supply Unit / Adapter 800 W*
550 W
Redundant Power Supply
AC Input Power Voltage 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)
Notes
  • Power supply specifications vary by hardware revision. An 800 W PSU is used in devices with serial numbers containing T2R (5th to 7th digits), while a 550 W PSU is in devices with ULR and VR4 serial numbers. For more information, refer to the Product Change Notice.
  • Power consumption is measured when it is fully loaded with Synology 8TB HAT5300-8T hard drive(s).
  • Noise Level Testing Environment: Fully loaded with Seagate 2TB ST2000VN000 hard drive(s) in the idle state. Two G.R.A.S. Type 40AE microphones, each set up 1 meter away from the Synology NAS at the front and rear. Background noise: 16.49-17.51 dB(A); Temperature: 24.25-25.75˚C; Humidity: 58.2-61.8%
Temperature
Temperature
 Operating Temperature 0°C to 35°C (32°F to 95°F)
Storage Temperature -20°C to 60°C (-5°F to 140°F)
Relative Humidity 5% to 95% RH
Certification
Certification
  • FCC
  • CE
  • BSMI
  • VCCI
  • RCM
  • EAC
  • CCC
  • KC
  • UL
Warranty
Warranty
 5 Years
Notes The warranty period starts from the purchase date as stated on your purchase receipt. (Learn more)
Environment
Environment
 RoHS Compliant
Packaging Content
Packaging Content
  • Main Unit X 1
  • Accessory Pack X 1
  • AC Power Cord X 2
  • Quick Installation Guide X 1
Optional Accessories
Optional Accessories
Notes All memory modules will operate at the maximum frequency specified by the CPU manufacturer.

Notes:

  1. Model specifications are subject to change without prior notice.
  2. The figures are based on Synology internal testing. Each performance test is done individually. No other services or applications are processed at the same time.
  3. The actual performance may be lower than lab testing figure due to differences in server configuration, deployment, and the number of active operations.
  4. If usage requirements exceed the specifications above, please contact our regional partners for professional advice.