Synology RackStation RS4021xs+ 16-Bay Rackmount NAS

The Synology RackStation RS4021xs+ is a high-performance 16-bay 3U rackmount NAS designed for centralized file storage, backup, business workloads, virtualization support, surveillance storage, and scalable rack-based data management.

With an Intel Xeon D-1541 8-core processor, 16GB DDR4 ECC UDIMM memory, support for up to 64GB memory, 16 drive bays, expansion support up to 40 drive bays with two RX1217 or RX1217RP expansion units, 4 x 1GbE LAN ports, 2 x 10GbE LAN ports, 2 x USB 3.2 Gen 1 ports, 2 x Infiniband expansion ports, 2 x PCIe Gen3 x8 slots with x8 link, redundant power supply support, and compatibility with 3.5" SATA HDDs and 2.5" SATA SSDs, the RS4021xs+ is built for demanding business and enterprise storage environments.

Product Overview

The Synology RackStation RS4021xs+ is designed for customers who need a high-capacity, high-performance rackmount NAS solution for centralized data storage, file sharing, backup, surveillance, virtualization support, and business application workloads.

With sixteen drive bays as standard and expansion support up to forty drive bays when paired with two compatible RX1217 or RX1217RP expansion units, the RS4021xs+ gives businesses strong storage flexibility for growing data requirements.

Powered by an Intel Xeon D-1541 8-core / 16-thread processor with 2.1GHz base frequency and 2.7GHz turbo frequency, plus 16GB DDR4 ECC UDIMM memory, the RS4021xs+ supports Synology DSM features for storage management, file services, backup, Synology Drive, Synology Office, Synology Photos, MailPlus, Surveillance Station, Snapshot Replication, Synology High Availability, SAN Manager, Fibre Channel, and Virtual Machine Manager.

The RS4021xs+ also includes built-in dual 10GbE connectivity, two PCIe expansion slots, and redundant power supply support, making it suitable for businesses that need high network throughput, scalable storage, SSD cache options, and improved service continuity.

Key Features

• 16-bay Synology RackStation NAS
• 3U rackmount form factor
• Intel Xeon D-1541 processor
• 8-core / 16-thread CPU
• 2.1GHz base and 2.7GHz turbo CPU frequency
• 16GB DDR4 ECC UDIMM system memory
• Maximum memory capacity of 64GB with compatible memory expansion
• Hardware encryption engine
• Supports 3.5" SATA HDDs
• Supports 2.5" SATA SSDs
• Hot-swappable drive support
• Expands up to 40 drive bays with two RX1217 or RX1217RP expansion units
• 4 x RJ-45 1GbE LAN ports
• 2 x RJ-45 10GbE LAN ports
• 2 x USB 3.2 Gen 1 ports
• 2 x Infiniband expansion ports
• 2 x PCIe Gen3 x8 slots with x8 link
• Redundant power supply support
• Supports optional 10GbE and 25GbE network interface cards
• Supports optional M.2 SSD adapter card
• Supports SSD read/write cache
• Supports SSD TRIM
• Supports RAID F1, Basic, JBOD, RAID 0, RAID 1, RAID 5, RAID 6, and RAID 10
• Supports RAID Group
• Maximum single volume size of 108TB, 200TB with 32GB memory, or up to 1PB with 64GB memory for RAID 6 groups only
• Supports up to 285 IP cameras depending on codec, resolution, and configuration
• Supports 4-post 19" rack installation with optional Synology rail kit
• Backed by a 5-year warranty

Recommended Use Cases

• Business file storage
• Enterprise rackmount NAS deployment
• Centralized document backup
• Server and endpoint backup
• Virtualization storage
• iSCSI and Fibre Channel storage workflows
• Shared folder snapshots
• Synology Drive file access and synchronization
• Synology Office collaboration
• Synology Photos management
• MailPlus server workflows
• Surveillance storage
• SSD cache deployments
• Built-in 10GbE storage environments
• 25GbE network upgrade with compatible card
• High-capacity RAID storage configurations
• Storage expansion with RX1217 or RX1217RP
• Business continuity and data protection workflows
• Environments requiring redundant power supply protection

Specifications

• Brand: Synology
• Model: RS4021xs+
• Product Type: 16-Bay Rackmount NAS
• Form Factor: 3U
• CPU Model: Intel Xeon D-1541
• CPU Quantity: 1
• CPU Cores: 8
• CPU Threads: 16
• CPU Architecture: 64-bit
• CPU Frequency: 2.1GHz base / 2.7GHz turbo
• Hardware Encryption Engine: Yes
• System Memory: 16GB DDR4 ECC UDIMM
• Pre-installed Memory: 16GB x 1
• Total Memory Slots: 4
• Maximum Memory Capacity: 64GB
• Drive Bays: 16
• Maximum Drive Bays with Expansion Unit: 40 with RX1217 / RX1217RP x2
• Compatible Drive Type: 3.5" SATA HDD
• Compatible Drive Type: 2.5" SATA SSD
• Hot Swappable Drive: Yes
• LAN Port: 4 x RJ-45 1GbE
• LAN Port: 2 x RJ-45 10GbE
• USB Ports: 2 x USB 3.2 Gen 1
• Expansion Ports: 2
• Expansion Port Type: Infiniband
• PCIe Expansion: 2 x Gen3 x8 slots with x8 link
• Size: 132.3mm x 482mm x 656.5mm
• Weight: 17.4kg
• Rack Installation Support: 4-post 19" rack with Synology Rail Kit RKS-02
• System Fan: 80mm x 80mm x 3
• Fan Speed Modes: Full-Speed Mode, Cool Mode, Quiet Mode
• Easy Replacement System Fan: Yes
• Power Recovery: Yes
• Scheduled Power On / Off: Yes
• Wake on LAN / WAN: Yes
• Noise Level: 44.7 dB(A)
• Power Supply Unit / Adapter: 800W or 550W, depending on hardware revision
• Redundant Power Supply: Yes
• AC Input Power Voltage: 100V to 240V AC
• Power Frequency: 50/60Hz, Single Phase
• Power Consumption: 145.79W during access
• Power Consumption: 62.68W during HDD hibernation
• British Thermal Unit: 497.14 BTU/hr during access
• British Thermal Unit: 213.74 BTU/hr during HDD hibernation
• 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
• Certification: FCC, CE, BSMI, VCCI, RCM, EAC, CCC, KC, BIS, UL
• Environment: RoHS Compliant
• Warranty: 5 Years

Performance and Reliability Features

• 16-bay 3U RackStation NAS designed for demanding business and enterprise storage deployments
• Intel Xeon D-1541 8-core / 16-thread processor for compute-intensive DSM workloads
• 16GB DDR4 ECC UDIMM memory for enhanced data integrity
• Supports memory expansion up to 64GB using compatible Synology memory
• Hardware encryption engine support
• Supports 3.5" SATA HDDs and 2.5" SATA SSDs
• Hot-swappable drive support for easier drive maintenance
• Expansion support up to 40 drive bays with compatible RX1217 or RX1217RP expansion units
• Built-in dual 10GbE RJ-45 LAN ports for high-speed network storage access
• Four 1GbE LAN ports for additional network connectivity
• Two PCIe Gen3 x8 slots with x8 link for compatible network interface cards or adapter cards
• Supports optional 10GbE and 25GbE network interface cards
• Supports optional M.2 SSD adapter card
• Redundant power supply support to help keep services online if one power source has an issue
• Supports SSD read/write cache and SSD TRIM
• Supports Btrfs and ext4 file systems on internal drives
• Supports RAID F1, Basic, JBOD, RAID 0, RAID 1, RAID 5, RAID 6, and RAID 10
• Supports RAID Group
• Supports volume expansion with larger HDDs
• Supports volume expansion by adding a HDD for RAID F1, JBOD, RAID 5, and RAID 6
• Supports global hot spare for RAID F1, RAID 1, RAID 5, RAID 6, and RAID 10
• Supports maximum single volume size of up to 200TB with 32GB memory, or up to 1PB with 64GB memory for RAID 6 groups only
• Supports DSM file services including SMB, AFP, NFS, FTP, WebDAV, and Rsync
• Supports iSCSI and Fibre Channel workflows
• Supports virtualization storage with VMware vSphere, Microsoft Hyper-V, Citrix XenServer, and OpenStack
• Supports Snapshot Replication
• Supports Hyper Backup
• Supports Synology High Availability
• Supports Synology Drive for file access and synchronization
• Supports Synology Office collaboration workflows
• Supports Synology Photos facial recognition and object recognition
• Supports Synology MailPlus with included free email accounts
• Supports Virtual Machine Manager with recommended virtual machine instances
• Includes 2 default Surveillance Station licenses
• Supports up to 285 IP cameras depending on codec, resolution, and configuration
• 5-year warranty support

Compatibility Note

Please check that your selected hard drives, SSDs, memory upgrades, expansion units, network interface cards, M.2 SSD adapter cards, and rack accessories are compatible with the Synology RS4021xs+ before ordering.

This NAS supports 3.5" SATA HDDs and 2.5" SATA SSDs. Storage drives, SSDs, memory upgrades, expansion units, network cards, adapter cards, rack rail kits, and optional accessories are not included unless specifically stated by the seller.

Synology notes that full functionality, reliability, and performance are only guaranteed for Synology drives listed on the compatibility list. Non-validated components may limit certain functionality and may affect system stability.

For memory expansion, please use compatible Synology memory modules for optimum compatibility and reliability. For multi-module memory configurations, all modules must be identical and share the same model number.

Synology has the following optional accessories for this model: RX1217 / RX1217RP expansion units, Synology DDR4 ECC UDIMM memory, Synology HAT5300 Series 3.5" SATA HDDs, Synology SAT5200 Series 2.5" SATA SSDs, E10M20-T1 M.2 SSD and 10GbE combo adapter card, M2D20 M.2 SSD adapter card, E25G30-F2 25GbE network interface card, selected 10GbE network interface cards, and RKS-02 sliding rail kit.

Before ordering, please confirm:

• Your selected drives are compatible with the Synology RS4021xs+
• Your selected SSDs are compatible with the Synology RS4021xs+
• Your selected memory modules are compatible with the Synology RS4021xs+
• Your selected expansion units are compatible with the Synology RS4021xs+
• Your selected network interface card or adapter card is compatible with the Synology RS4021xs+
• Your rack installation requirements and rail kit compatibility
• Your required storage capacity matches your intended use
• Your intended RAID, file system, backup, or storage setup
• Your network and device compatibility requirements
• Your intended DSM package and workload requirements
• Whether multiple drives are required for your intended RAID configuration

What’s in the Box

• Synology RS4021xs+ main unit x1
• Accessory pack x1
• AC power cord x2
• Quick installation guide x1