High-end scalable NAS in desktop form factor

DS1621xs+ is a high-end NAS with server-class performance in a 6-bay desktop form factor. The built-in M.2 SSD cache slots, 10GbE port, expandable memory, and scalable storage design allow you to boost the performance of your NAS, making it ideal for small and medium-sized businesses that need an efficient and space-saving storage solution.

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CPU

Intel® Xeon D-1527 4-core 2.2 GHz

Memory

8 GB DDR4 ECC SODIMM, up to 32 GB

High Performance

Over 3,100 MB/s sequential read

Scalability

Up to 16 drives with DX5171

Supercharge your storage with speedy performance

DS1621xs+ comes with built-in M.2 SSD cache slots capable of providing I/O response speeds 20 times faster than hard drives without occupying front drive bays. The built-in 10GbE port provides fast data transmission and can be bonded with an additional network interface card for higher network bandwidth.

  • M.2 SSD support

    Dual M.2 2280 SSD supporting NVMe SSDs
  • 10GbE support

    Built-in 10GBASE-T for bandwidth intensive environments
  • M.2 SSD support
  • 10GbE support
  1. 1
  2. 2

5-year warranty

At Synology, we are committed to product innovation and quality. Synology guarantees a robust and reliable data management experience with a 5-year limited warranty, providing responsive technical support and hardware replacement services to maximize your return on investment.

Synology Replacement Service (SRS)

SRS provides free advance replacement units as early as the next business day in selected regions, maximizing the service uptime for your mission-critical storage and ensuring your business continuity.Check service availability here.

Ultimate Backup Solution

DS1621xs+ integrates various backup applications into an intuitive user interface, offering durable storage technologies to safeguard your valuable data on any device.

Active Backup for Business

Centralize backup tasks for VMware, Windows, and file servers. Restore whatever you want fast and reliably when needed.
Learn more

Hyper Backup

Comprehensively back up your data to a local shared folder, an external device, another Synology NAS, an rsync server, or a public cloud to ensure data safety.
Learn more

Synology Drive

Safeguard your computer with Synology Drive Client. Effortlessly perform real-time data backups and point-in-time file recovery.
Learn more

Active Backup for
Microsoft 365 / G Suite

On-premise backup solution with a centralized dashboard. Optimize storage efficiency with single instancing and block-level deduplication technology.
Microsoft 365G Suite

Real-time collaboration on your private cloud

Synology Office is a collaboration package combining the convenience and usability of public clouds with the data privacy and security guaranteed by private clouds. It allows you to work seamlessly together on documents and spreadsheets in a protected environment. Learn more

Real-time collaboration on the same online documents to boost productivity,

Instant communication on Synology Chat during the editing of documents or spreadsheets

Version control for you to navigate all the changes and retrieve previous versions with just a click

  1. Real-time collaboration on the same online documents to boost productivity,
  2. Instant communication on Synology Chat during the editing of documents or spreadsheets
  3. Version control for you to navigate all the changes and retrieve previous versions with just a click

Virtual Machine Manager

Virtual Machine Manager enables you to test new software in sandboxes, isolate your customers' machines, and increase the flexibility of your server. You can easily run Windows, Linux, and Virtual DSM on your Synology NAS by just a few steps. Learn more

Snapshots for virtual machines

Perfectly clone and restore a virtual machine within seconds.

Live migration

Seamlessly migrate Virtual DSM instances from a Synology NAS to another.

Multi-tenant environment

Create multiple isolated virtual machines for subsidiary business units or departments.

Powered by Synology DSM

Central Management System

Manage multiple Synology NAS servers simultaneously on a centralized interface to increase business efficiency.

Learn more

Synology MailPlus

Secure, reliable, and private mail server solution with an intuitive and modern mail client.

Learn more

Synology High Availability

Seamless transition between clustered servers in the event of a server failure to minimize the impact on applications.

Learn more

Security

Comprehensive built-in security tools are constantly updated to protect your devices against evolving threats.

Learn more

Synology Drive

A versatile solution for file management and synchronization. 

Learn more

Surveillance Station

Complete surveillance solution for recording, monitoring, and management.

Learn more
  • 1 Status indicator
  • 2 Alert indicator
  • 3 Power button and indicator
  • 4 LAN indicator
  • 5 Drive status indicator
  • 6 Drive tray
  • 7 Drive tray lock
  • 8 USB 3.0 port
  • 9 System fan
  • 10 Power port
  • 11 Kensington Security Slot
  • 12 10GbE RJ-45 port
  • 13 1GbE RJ-45 port
  • 14 Reset button
  • 15 Expansion port
  • 16 PCIe expansion slot

Notes:

  1. DS1621xs+ can be scaled up to 16 drives with 2 x DX517. Synology expansion units are sold separately.

Hardware Specifications

CPU

CPU

CPU Model Intel Xeon D-1527
CPU Architecture 64-bit
CPU Frequency 4-core 2.2 (base) / 2.7 (turbo) GHz
Hardware Encryption Engine (AES-NI)

Memory

Memory

System Memory 8 GB DDR4 ECC SODIMM
Memory Module Pre-installed 8 GB (8 GB x 1)
Total Memory Slots 2
Maximum Memory Capacity 32 GB (16 GB x 2)
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 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.

Storage

Storage

Drive Bays 6
Maximum Drive Bays with Expansion Unit 16 (DX517 x 2)
M.2 Drive Slots 2 (NVMe)
Compatible Drive Type* (See all supported drives)
  • 3.5" SATA HDD
  • 2.5" SATA HDD
  • 2.5" SATA SSD
  • M.2 2280 NVMe SSD
Maximum Single Volume Size*
  • 200 TB (32 GB RAM required, for RAID 5 or RAID 6 groups only)
  • 108 TB
Hot Swappable Drive
Notes
  • "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

External Ports

RJ-45 1GbE LAN Port 2 (with Link Aggregation / Failover support)
RJ-45 10GbE LAN Port 1
USB 3.0 Port 3
eSATA Port 2

PCIe

PCIe

PCIe Expansion 1 x Gen3 x8 slot (x8 link)

File System

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

Appearance

Size (Height x Width x Depth) 166 mm x 282 mm x 243 mm
Weight 5.3 kg

Others

Others

System Fan 92 mm x 92 mm x 2 pcs
Fan Speed Mode
  • Full-Speed Mode
  • Cool Mode
  • Quiet Mode
Easy Replacement System Fan
Brightness Adjustable Front LED Indicators
Power Recovery
Noise Level* 25.2 dB(A)
Scheduled Power On / Off
Wake on LAN / WAN
Power Supply Unit / Adapter 250 W
AC Input Power Voltage 100 V to 240 V AC
Power Frequency 50/60 Hz, Single Phase
Power Consumption* 62.85 W (Access)
34.26 W (HDD Hibernation)
British Thermal Unit 214.45 BTU/hr (Access)
116.89 BTU/hr (HDD Hibernation)
Notes
  • Power consumption is measured when it is fully loaded with Western Digital 1TB WD10EFRX 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 40°C (32°F to 104°F)
Storage Temperature -20°C to 60°C (-5°F to 140°F)
Relative Humidity 5% to 95% RH

Certification

Certification

  • FCC
  • CE
  • BSMI
  • EAC
  • CCC
  • KC
  • VCCI
  • RCM

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 1
  • RJ-45 LAN Cable 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.

DSM Specifications

Storage Management

Storage Management

Maximum Internal Volume Number 256
Maximum iSCSI Target Number 256
Maximum iSCSI LUN 512
iSCSI LUN Clone/Snapshot, Windows ODX
SSD Read / Write Cache (White Paper)
SSD TRIM
RAID Group
Supported RAID Type
  • RAID F1
  • Basic
  • JBOD
  • RAID 0
  • RAID 1
  • RAID 5
  • RAID 6
  • RAID 10
RAID Migration
  • Basic to RAID 1
  • Basic to RAID 5
  • RAID 1 to RAID 5
  • RAID 5 to RAID 6
Volume Expansion with Larger HDDs
  • RAID F1
  • RAID 1
  • RAID 5
  • RAID 6
  • RAID 10
Volume Expansion by Adding a HDD
  • RAID F1
  • JBOD
  • RAID 5
  • RAID 6
Global Hot Spare Supported RAID Type
  • RAID F1
  • RAID 1
  • RAID 5
  • RAID 6
  • RAID 10

File Services

File Services

File Protocol CIFS/AFP/NFS/FTP/WebDAV
Maximum Concurrent CIFS/AFP/FTP Connections 2,000
Maximum Concurrent CIFS/AFP/FTP Connections (with RAM expansion) 8,000
Windows Access Control List (ACL) Integration
NFS Kerberos Authentication
Notes
  • Regarding data concerning tests with RAM expansion, all memory slots are installed with the maximum capacity of supported RAM.
  • During testing, the maximum number of SSDs supported by this model is installed in a RAID 5 configuration.

Account & Shared Folder

Account & Shared Folder

Maximum Local User Accounts 16,000
Maximum Local Groups 512
Maximum Shared Folder 512
Maximum Shared Folder Sync Tasks 32

High Availability

High Availability

Synology High Availability

Log Center

Log Center

Syslog Events per Second 1,500

Virtualization

Virtualization

VMware vSphere 6 with VAAI
Windows Server 2016
Windows Server 2019
Citrix Ready
OpenStack

General Specifications

General Specifications

Networking Protocols SMB1 (CIFS), SMB2, SMB3, NFSv3, NFSv4, NFSv4.1, NFS Kerberized sessions, iSCSI, HTTP, HTTPs, FTP, SNMP, LDAP, CalDAV
Supported Browsers
  • Google Chrome
  • Firefox
  • Microsoft Edge
  • Internet Explorer 10 onwards
  • Safari 10 onwards
  • Safari (iOS 10 onwards)
  • Google Chrome (Android 6.0 onwards)
Supported Language English, Deutsch, Français, Italiano, Español, Dansk, Norsk, Svenska, Nederlands, Русский, Polski, Magyar, Português do Brasil, Português Europeu, Türkçe, Český, ภาษาไทย, 日本語, 한국어, 繁體中文, 简体中文

Add-on Packages view the complete package list

Antivirus by McAfee (Trial)

Antivirus by McAfee (Trial)

Central Management System

Central Management System

Synology Chat

Synology Chat

Maximum Users 4,000
Notes
  • The number of concurrent HTTP connections for Synology Chat was configured to the maximum.
  • CPU and RAM usage were both under 80% when the number of maximum users was reached.
  • For tested models with expandable memory, the maximum amount of RAM was installed.

Document Viewer

Document Viewer

Download Station

Download Station

Maximum Concurrent Download Tasks 80

exFAT Access (Optional)

exFAT Access (Optional)

Synology MailPlus / MailPlus Server

Synology MailPlus / MailPlus Server

Free Email Accounts 5 (Licenses required for additional accounts)
Maximum Number of Concurrent Users 450
Maximum Server Performance 3,363,000 emails per day, approx. 102GB
Notes
  • The CPU and RAM usage were both under 80% when testing the maximum number of concurrent users.
  • Models with more than 4 bays were installed with two SSDs for SSD cache.
  • For tested models with expandable memory, the maximum amount of RAM was installed.
  • The performance of the mail system will slightly decrease in high-availability mode due to data synchronization between the two servers.
  • Functions that were enabled in all of the tests above: anti-spam, anti-virus, DNSBL, greylist, content scan, full-text search (English only).

Media Server

Media Server

DLNA Compliance

Moments

Moments

Facial Recognition
Subject Recognition
Auto Color & Rotate
Moments Select

Snapshot Replication

Snapshot Replication

Maximum Snapshots per Shared Folder 1,024
Maximum of System Snapshots 65,536

Surveillance Station

Surveillance Station

Maximum IP cam (Licenses required) 75 (including 2 Free License) (See All Supported IP Cameras)
Total FPS (H.264) 2250 FPS @ 720p (1280x720)
1050 FPS @ 1080p (1920x1080)
600 FPS @ 3M (2048x1536)
400 FPS @ 5M (2591x1944)
280 FPS @ 4K (3840x2160)
Total FPS (H.265) 2250 FPS @ 720p (1280x720)
2250 FPS @ 1080p (1920x1080)
1125 FPS @ 3M (2048x1536)
700 FPS @ 5M (2591x1944)
490 FPS @ 4K (3840x2160)
Notes
  • Surveillance Station throughput is tested with Axis network camera, using continuous recording with live view from Surveillance Station and motion detection by camera. Live view and recording are sharing the same stream from the camera.
  • The maximum channel number also includes devices installed on Virtual DSM.
  • Total FPS may be affected by other services running at the same time (e.g., archive tasks performed by Archive Vault).

Synology Drive

Synology Drive

Recommended Number of Hosted Files 3,000,000 (applies to files indexed or hosted by Synology Drive. For file access through other standard protocols, refer to the File Services section above)
Recommended Number of Concurrent Sync Clients 900 (the number of connections that can be maintained when the recommended number of hosted files was reached)
Notes
  • For tested models with expandable memory, the maximum amount of RAM was installed. (Utilizing SSD cache can significantly improve performance.)
  • Exceeding the recommended numbers above will not block application operations, but may result in longer response time.
  • Btrfs file system and non-encrypted shared folders were used during the aforementioned testing.

Synology Office

Synology Office

Maximum Users 2,900
Notes
  • Multiple files were opened for testing and each file was edited by 30 users simultaneously.
  • CPU and RAM usage were both under 80% when the number of maximum users was reached.
  • For tested models with expandable memory, the maximum amount of RAM was installed.
  • Client performance may affect maximum simultaneous editing users. Client PCs used for testing: Intel Core i3-3220 / 8GB RAM

Video Station

Video Station

Virtual Machine Manager

Virtual Machine Manager

Recommended Virtual Machine Instances 8 (Learn more)
Recommended Virtual DSM Number (Licenses required) 8 (including 1 Free License)
Notes The specifications vary depending on system configuration and memory size.

VPN Server

VPN Server

Maximum Connections 40

Notes:

  • Model specifications are subject to change without prior notice.
  • 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.
  • The actual performance may be lower than lab testing figure due to differences in server configuration, deployment, and the number of active operations.
  • If usage requirements exceed the above recommended specifications, please contact us.