Synology RS4021xs+ RackStation 16-bay NAS server

Built to Handle Intensive Workloads

Synology RackStation 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 units

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 VM.

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 Workspace 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 cameras.
• 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