DiskStation DS1821+

High capacity storage and data protection for anyone

DS1821plus
DS1821plus
CPU

CPU

AMD Ryzen
Quad-core 2.2 GHz

Cache Acceleration

Cache Acceleration

Dual M.2 2280 slots for NVMe Cache

Performance

Performance

113K 4K random read IOPS1

Scalability

Scalability

Expand up to 18 drives
with two DX517 expansion units

The performance you need

Reduce transfer times with the DS1821+, designed to accelerate your workloads. Easily add faster networking and NVMe drives to further boost performance.

Up to 2,322/1,460 MB/s read/write2

Up to 10GbE networking3

2 x M.2 NVMe cache & storage pool4

The performance you need

Storage that fits your needs

Make the most of high-performance networking and file access without taking up unnecessary space. DS1821+ comes equipped with 8 bays and can scale up to 18 bays with 2 DX517 expansion units as your data needs grow.5

5 bays15 bays

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108 TB252 TB

Storage that fits your needs

Ultimate Backup Solution

DS1821+ 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

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

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

Drive Package

Drive Package

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

Active Backup for<br>Microsoft 365 / Google Workspace Active Backup for<br>Microsoft 365 / Google Workspace

Active Backup for
Microsoft 365 / Google Workspace

Protect corporate data stored on the cloud. On-premise backup solution with a centralized dashboard. Optimize storage efficiency with single instancing and block-level deduplication technology.
Microsoft 365Google Workspace

Extra protection with Extended Warranty Plus

Extend the standard 3-year hardware warranty of your DS1821+ with 2 more years of Synology-certified support and premium services that help you recover faster in the event of disaster.

Powered by Synology DiskStation Manager

Works best with Synology drives

Engineered to handle intensive 24/7 workloads, Synology drives consistently deliver top-grade performance.

Works best with Synology drives

DiskStation DS1821+

product DS1821plus front view photo
product DS1821plus back view photo
  • 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 3.2 Gen 1 port
  • 9 Power port
  • 10 System fan
  • 11 PCIe expansion slot
  • 12 Kensington Security Slot
  • 13 Expansion port
  • 14 1GbE RJ-45 port
  • 15 Reset button
  • 16 USB 3.2 Gen 1 port

Notes:

  1. Performance figures are achieved in the Synology lab with optimized network and configuration settings. Actual performance could vary in different environments. Comparison done against prior-generation 8-bay DS1819+. For full details on the test setup, please visit the Synology performance page here.

  2. Performance figures are obtained through SMB sequential throughput tests using Windows Server 2016 Datacenter on a a DS1821+ with a Synology 10GbE NIC and SSD. Actual performance may vary depending on the testing environment, usage, and configuration. See performance charts for more information.

  3. PCIe add-in cards, expansion units, and storage drives are sold separately. Refer to the compatibility list for compatible devices.

  4. Synology SNV3400 series M.2 NVMe SSD drives can be installed through the built-in M.2 slots to enable SSD caching or create SSD storage pools. Drives are sold separately.

  5. Storage figure calculated based on a RAID 5 configuration. Total storage capacity may vary depending on hard drives used and RAID configuration.

Hardware Specifications
CPU
CPU
CPU Model AMD Ryzen V1500B
CPU Quantity 1
CPU Architecture 64-bit
CPU Frequency 4-core 2.2 GHz
Hardware Encryption Engine (AES-NI)
Memory
Memory
System Memory 4 GB DDR4 ECC SODIMM
Memory Module Pre-installed 4 GB (4 GB x 1)
Total Memory Slots 2
Maximum Memory Capacity 32 GB (16 GB x 2)
Notes
  • 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.
  • 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 about the recommended memory configurations, please check the Hardware Installation Guide of your Synology product.
Storage
Storage
Drive Bays 8
Maximum Drive Bays with Expansion Unit 18 (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
Hot Swappable Drive*
Notes
  • The hot swappable drive feature is not supported by M.2 SSD slots.
  • "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.
External Ports
External Ports
RJ-45 1GbE LAN Port 4 (with Link Aggregation / Failover support)
USB 3.2 Gen 1 Port* 4
eSATA 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
PCIe Expansion 1 x Gen3 x8 slot (x4 link)
File System
File System
Internal Drives
  • Btrfs
  • EXT4
External Drives
  • Btrfs
  • EXT4
  • EXT3
  • FAT
  • NTFS
  • HFS+
  • exFAT
Notes exFAT Access can be installed for free from Package Center in DSM 7.0. In DSM 6.2 or earlier versions, exFAT Access needs to be purchased in Package Center.
Appearance
Appearance
Size (Height x Width x Depth) 166 mm x 343 mm x 243 mm
Weight 6 kg
Others
Others
System Fan 120 mm x 120 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* 22.2 dB(A)
Scheduled Power On / Off
Wake on LAN / WAN
Power Supply Unit / Adapter 250 W
AC Input Power Voltage 100V to 240V AC
Power Frequency 50/60 Hz, Single Phase
Power Consumption 59.8 W (Access)
26.18 W (HDD Hibernation)
British Thermal Unit 204.05 BTU/hr (Access)
89.33 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
3-year hardware warranty, extendable to 5 years with EW201 or Extended Warranty Plus
Notes
  • Availability varies by region. Before purchasing, please visit the official web pages of EW201/202 and Extended Warranty Plus for a list of eligible regions.
  • 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
Maximum Single Volume Size* 108 TB
Maximum Internal Volume Number 64
M.2 SSD Storage Pool Support*
SSD Read / Write Cache (White Paper)
SSD TRIM
Supported RAID Type
  • Synology Hybrid RAID
  • 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
  • Synology Hybrid RAID
  • RAID 1
  • RAID 5
  • RAID 6
  • RAID 10
Volume Expansion by Adding a HDD
  • Synology Hybrid RAID
  • JBOD
  • RAID 5
  • RAID 6
Global Hot Spare Supported RAID Type
  • Synology Hybrid RAID
  • RAID 1
  • RAID 5
  • RAID 6
  • RAID 10
Notes
  • Creating M.2 storage pools requires the use of Synology-verified SSDs, which are rigorously tested under extreme temperature conditions. Thermal parameters for SSDs and NAS units are fine-tuned to ensure optimal management of thermal conditions under I/O-intensive environments. (Learn more)
  • Usable capacity for each volume will be lower than the maximum volume size and is dependent on the filesystem and the amount of system metadata stored.
  • Each internal volume (may consist of multiple drives) is expandable up to 108TB.
File Protocol SMB/AFP/NFS/FTP/WebDAV
Maximum Concurrent SMB/AFP/FTP Connections 1,000
Maximum Concurrent SMB/AFP/FTP Connections (with RAM expansion) 2,000
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.
  • The testing standard was based on the maximum number of concurrent connections supported by this model. During the testing, 25% of the connections were used to transfer files concurrently. The transfer process guaranteed that the connections were not interrupted; the minimum transfer speed was not guaranteed.
Maximum Local User Accounts 2,048
Maximum Local Groups 256
Maximum Shared Folder 512
Maximum Shared Folder Sync Tasks 16
Maximum Hybrid Share Folders 10
Data & Folder Backup
Entire System Backup
Notes DSM version requirement to support entire system backup: DSM7.2 or later.
Synology High Availability
Syslog Events per Second 1,000
Virtualization
Virtualization
VMware vSphere with VAAI
Windows Server 2016
Windows Server 2019
Citrix Ready
OpenStack
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
  • Safari
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
Notes For an updated list of supported browser versions, check the DSM Technical Specifications.
Antivirus by McAfee (Trial)
Antivirus by McAfee (Trial)
Maximum Users 1,500
Maximum Number of Concurrent Users 150
Notes When applicable, systems are tested configured with maximum memory and set to allow the maximum number of connections.
Document Viewer
Document Viewer
Download Station
Download Station
Maximum Concurrent Download Tasks 80
Maximum iSCSI Target Number 128
Maximum LUN 256
LUN Clone/Snapshot, Windows ODX
Notes iSCSI Manager has been renamed to SAN Manager in DSM 7.0.
Free Email Accounts 5 (Licenses required for additional accounts)
Maximum Number of Concurrent Users 150
Maximum Server Performance 1,484,000 emails per day, approx. 45GB
Notes
  • 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).
DLNA Compliance
Facial Recognition
Maximum Snapshots per Shared Folder 1,024
Maximum of System Snapshots 65,536
Maximum IP cam (Licenses required) 40 (including 2 Free License) (see all supported IP cameras)
Total FPS (H.264) 1200 FPS @ 720p (1280x720)
1050 FPS @ 1080p (1920x1080)
600 FPS @ 3M (2048x1536)
440 FPS @ 5M (2591x1944)
320 FPS @ 4K (3840x2160)
Total FPS (H.265) 1200 FPS @ 720p (1280x720)
1200 FPS @ 1080p (1920x1080)
1120 FPS @ 3M (2048x1536)
600 FPS @ 5M (2591x1944)
480 FPS @ 4K (3840x2160)
Notes
  • Maximum IP cameras and FPS figures are tested with the device fully populated with drives and under a continuous recording setup.
  • Actual system capabilities may differ depending on system configuration, drive performance, number of features enabled, and if additional workloads are present.
Recommended Number of Concurrent Sync Clients 550 (the number of connections that can be maintained when the recommended number of hosted files was reached)
Recommended Number of Hosted Files 50,000,000 (applies to files indexed or hosted by Synology Drive. For file access through other standard protocols, refer to the File Services section above)
Notes
  • Exceeding the recommended numbers above will not block application operations, but may result in longer response time.
  • Utilizing SSD cache can significantly improve performance.
  • For tested models with expandable memory, the maximum amount of RAM was installed.
  • Btrfs file system and non-encrypted shared folders were used during the aforementioned testing.
Maximum Users 1,800
Notes
  • Multiple files were opened for testing and each file was edited by 30 users simultaneously.
  • 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
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.
Maximum Connections 40

Notes:

  1. Model specifications are subject to change without prior notice.
  2. 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.
  3. The actual performance may be lower than lab testing figure due to differences in server configuration, deployment, and the number of active operations.
  4. If usage requirements exceed the specifications above, please contact our regional partners for professional advice.