synology Rack Station RS4021xs+

Highlights

Accelerated Performance

• Up to 234,698 random read IOPS and 6,258 MB/s sequential read performance1

 Powerful Compute

• Host multiple compute-intensive services with its 8-core Intel® processor

 Upgradability

• Two PCIe expansion slots allow for M.2 NVMe cache adapters and high-bandwidth network cards2

 Redundant Power

• Ensure business continuity with two redundant  power supplies

 On-demand Scalability

• Supports up to 40 drive bays using two RX1217(RP)3

Built to Handle Intensive Workloads

• Synology Rack Station RS4021xs+ is built to deliver exceptional performance, flexibility, and scalability for demanding enterprise environments.
•  Up to 234,698 4K random read IOPS and 6,258 MB/s sequential read performance for demanding workloads1
•  Featuring 16 drive bays supporting both SATA HDD/SSD 2.5/3.5" drives4, expandable to 40 bays using two Synology RX1217(RP) expansion units3

Optimized for Data Protection and Integrity

• Powered by Synology DSM, our unified data management operating system, and built upon the Btrfs file system, data stored on the RS4021xs+ is safely guarded by modern data protection technologies.

Advanced snapshots technology

• provides schedulable and near-instantaneous data protection of shared folders and LUNs

 File and folder-level data restoration

• enables restoration of specific files or folders

 Flexible storage quota system

• helps admins effortlessly manage available space by specifying storage limits for shared folders

 File self-healing

• detects and recovers corrupted files using mirrored metadata and RAID configurations

Inline compression

• compresses data before writing it to the drive, reducing write commands and optimizing storage space

Virtualization and Certified Storage

• DSM streamlines the provisioning and management of storage for virtual machines (VM). Certified for VMware® vSphere™, Microsoft® Hyper-V®, Citrix® XenServer™, and OpenStack, it integrates with your virtualization platform of choice through iSCSI or NFS protocols. Install Synology Storage Console on VMware or Windows platforms for additional management convenience and functionality right in the hypervisor.

Synology Virtual Machine Manager (VMM)

• is a hosted hypervisor for virtual machines running Windows®, Linux®, or virtualized versions of DSM with recovery mechanisms that ensure data protection on each VM5.

Data Backup Solutions for IT Infrastructure

Synology Active Backup Suite

• is a collection of license-free backup solutions built to protect Windows PCs and servers, VMs, other file servers, and cloud-based storage.

Active Backup for Business (ABB)

• consolidates backup tasks for physical and virtual environments and enables rapid restoration of files, entire physical machines, and VMs.

Active Backup for Google Workspace

• enables backup of Google data including Gmail, Contacts, Calendar, and Drive.

Active Backup for Microsoft 365

• enables backup of Microsoft 365 data including OneDrive for Business, SharePoint Online, emails, contacts, and calendar.

On-Premises Collaboration

• Synology's collaboration suite is a private SaaS for file sharing, concurrent document editing, emails, instant messaging, and more. By leveraging a private cloud infrastructure, it ensures data ownership while multilayered security enables secure multi-platform access.

Synology Drive

• allows data access, synchronization, on-demand file restoration, and backup.

Synology MailPlus6

• provides a secure, reliable, and private email server.

Synology Chat

• brings teams together through instant multi-platform communication.

Synology Calendar

• helps teams keep track of what is most important with convenient calendar sharing and scheduling.

Private Video Surveillance

• With Synology Surveillance Station, the RS4021xs+ becomes a powerful Network Video Recorder solution with support for up to 90 IP cameras7.
• 7,900+ supported camera models
• ONVIF support to prevent vendor lock-in
•  Private, subscription-free storage of the recordings
• Access through web browser, dedicated desktop clients, or mobile app
•  Event-based rules to trigger specific actions
•  Email, SMS, or push notification systems

Technical Specifications 

Hardware 

CPU

• Intel® Xeon® D-1541 8-core (16-thread) 2.1 GHz, Turbo Boost up to 2.7 GHz

Hardware encryption engine

• Yes (AES-NI) 

Memory

• 16 GB DDR4 ECC UDIMM (expandable up to 64 GB)

Compatible drive types

•  16 x 3.5" or 2.5" SATA HDD/SSD (drives not included)
• It is strongly recommended that you only install drives listed on your device's compatibility list4. Storage pool and volume creation processes may fail when using unverified drives. Synology is unable to provide technical support for devices using unsupported components. 

Hot swappable drive

• Yes

External ports 

• 2 x USB 3.2 Gen 1 ports
• 2 x Expansion ports (Infiniband)

Form factor

• Rackmount 3U

Size (HxWxD)

• 132.3 x 482 x 656.5 mm (with server handles)

Weight

• 17.4 kg

LAN ports

•  4 x 1GbE RJ-45
• 2 x 10GbE RJ-45

Wake on LAN/WAN

• Yes

PCIe 3.0 slots 

• 2 x 8-lane x8 slots
•  Supports 10GbE/25GbE network interface cards2 and M.2 NVMe SSD adapter cards for SSD cache9

Scheduled power 0n/off

• Yes

System fans

• 3 x (80 x 80 x 32 mm)

AC input power voltage

• 100 V to 240 V AC

Power frequency

• 50/60 Hz, single phase

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

Maximum operating altitude

• 5,000 m (16,400 ft)

General DSM Specification

Networking protocols

• SMB, AFP, NFS, FTP, WebDAV, CalDAV, iSCSI, Telnet, SSH, SNMP, VPN (PPTP, OpenVPN™, L2TP)

File systems

• Internal: Btrfs, ext4
• External: Btrfs, ext4, ext3, FAT32, NTFS, HFS+, exFAT9

Supported RAID types

• Synology RAID F1, Basic, JBOD, RAID 0, RAID 1, RAID 5, RAID 6, RAID 10

Storage management

•  Maximum single volume size: 108/200 TB10
•  Maximum system snapshots: 65,53611
•  Maximum internal volumes: 256

SSD cache

•  Read/write cache support
•  2.5" SATA SSD support
•  M.2 NVMe SSD support8

File sharing capabilities

• Maximum local user accounts: 16,000
•  Maximum local groups: 512
•  Maximum shared folders: 512
• Maximum concurrent SMB/NFS/AFP/FTP connections: 4,00012

Privileges

• Windows Access Control List (ACL), application privileges

Directory services

• Connects with Windows AD/LDAP servers enabling domain users to login via SMB/NFS/AFP/FTP/File Station using their  existing credentials.

Virtualization

• VMware vSphere, Microsoft Hyper-V, Citrix, OpenStack

Security

• Firewall, shared folder encryption, SMB encryption, FTP over SSL/TLS, SFTP, rsync over SSH, login auto block, Let's Encrypt support, HTTPS (customizable cipher suite) 

Supported clients

• Windows® 7 onwards, macOS® 10.12 onwards

Supported browsers

• Chrome, Firefox, Edge, Internet Explorer 10 onwards, Safari 10 onwards, Safari (iOS 10 onwards), Chrome (Android™ 6.0 \onwards) on tablets