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 throughput. 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.
Compute
Intel® Xeon® D-1541 8-core 2.1 GHz
Networking
Built-in dual-port 10GbE
Memory
16 GB ECC DDR4 Up to 64 GB
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
Customize to your business
The RS4021xs+ includes two PCIe slots for performance, networking, and storage upgrades enabling it to adapt to any business environment.
Double bandwidth
Upgrade network bandwidth in minutes by 2x or more with Synology's range of 10GbE NICs.
SSD cache
Boost read/write IOPS by up to 16 times by enabling SSD cache with our Synology M.2 NVMe adapter cards and SNV3500 SSDs, or by installing one or more 2.5" SAT5200 SSDs.
Storage expansion
Quickly and easily scale up to 40 drives with two RX1217(RP) expansion units.
The ultimate backup solutions - license-free
Keep disaster at bay
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. Deduplication, 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
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
CPU
CPU Model
Intel Xeon D-1541
CPU Architecture
64-bit
CPU Frequency
8-core 2.1 (base) / 2.7 (turbo) GHz
Hardware Encryption Engine (AES-NI)
Yes
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
- 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 on the recommended memory configurations, visit here.
- Synology reserves the right to replace memory modules with the same or higher frequency based on suppliers product life cycle status. Rest assured that the compatibility and stability have been strictly verified with the same benchmark to ensure identical performance.
Storage
Drive Bays
16
Maximum Drive Bays with Expansion Unit
40 (RX1217/RX1217RP x 2)
Compatible Drive Type
3.5" SATA HDD
2.5" SATA SSD
Maximum Single Volume Size
200 TB (32 GB RAM required, for RAID 5 or RAID 6 groups only)
108 TB
Hot Swappable Drive
Yes
Notes
- Storage Pool and volume creation require all drives to be listed as compatible on the device models compatibility list.
- "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.
- Each internal volume (may consist of multiple drives) is expandable up to 108 TB (with memory less than 32 GB) or 200 TB (with memory equal to or greater than 32 GB).
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 Expansion
2 x Gen3 x8 slots (x8 link)
File System
Internal Drives
Btrfs
EXT4
External Drives
Btrfs
EXT4
EXT3
FAT
NTFS
HFS+
exFAT
Notes
exFAT Access is purchased separately in Package Center.
Appearance
Form Factor (RU)
3U
Rack Installation Support
4-post 19" rack (Synology Rail Kit - RKS1317)
Notes
The rail kit is sold separately
Others
System Fan
80 mm x 80 mm x 3 pcs