Synology Inc.

Refurbished DiskStation DS1821+

High capacity storage and data protection for anyone

Synology Certified Refurbished

Access Synology solutions in a cost-effective and environmentally responsible way. All certified refurbished products are put through extensive testing, comply with stringent quality standards, and come with a 2-year warranty.

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Designed for scalability and performance

The 8-bay Synology DS1821+ is aimed at IT enthusiast and SMB customers looking for a powerful and scalable storage solution, its business-grade backup solutions keep users safe and protected from potential data loss, while major improvements to compute capabilities and throughput means workloads are finished faster than ever before.

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CPUAMD Ryzen^™
Quad-core 2.2 GHz

Cache AccelerationDual M.2 2280 slots for NVMe Cache

Performance113K 4K random read IOPS

ScalabilityExpand 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.

The DS1821+ achieves up to 2,323 MB/s read and 1,460 MB/s write speeds

This device can be configured with up to 25GbE networking

The DS1821+ features two M.2 NVMe slots for caching or storage pool creation

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.

It supports up to 300 TB of storage capacity after expansion when using 16 TB drives in a RAID 5 configuration

Fully certified storage virtualization solutions

Synology iSCSI storage fully supports most virtualization solutions to enhance work efficiency with easy management interface. VMware vSphere 6 and VAAI integration helps offload storage operations and optimizes computation efficiency. Windows Offloaded Data Transfer (ODX) speeds up data transfer and migration rate. OpenStack Cinder support turns your Synology NAS into a block-based storage component.

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

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

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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.

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Drive Package

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

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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 365 Google Workspace

Powered by Synology DiskStation Manager

Central Management System

Conveniently manage your fleet of Synology NAS from a centralized console.

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Synology MailPlus

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

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Synology High Availability

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

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Security

Shield your Synology NAS from the most sophisticated threats with industry-leading security solutions.

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Synology Drive

Instantly access your NAS files across multiple devices whenever you want, wherever you are.

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Surveillance

Protect your home or business with intelligent monitoring and video management tools.

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Works best with Synology drives

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

HDD

Enterprise Series 3.5" SATA

Plus Series 3.5" SATA

SSD

Enterprise Series 2.5" SATA

Enterprise Series M.2 NVMe

Hardware Overview

1Status indicator
2Alert indicator
3Power button and indicator
4LAN indicator

5Drive status indicator
6Drive tray
7Drive tray lock
8USB 3.2 Gen 1 port

9Power port
10System fan
11PCIe expansion slot
12Kensington Security Slot

13Expansion port
141GbE RJ-45 port
15Reset button
16USB 3.2 Gen 1 port

Notes: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.Performance figures are obtained through SMB sequential throughput tests using Windows Server 2016 Datacenter on 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.PCIe add-in cards, expansion units, and storage drives are sold separately. Refer to the compatibility list for compatible devices.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.Storage figure calculated based on a RAID 5 configuration. Total storage capacity may vary depending on hard drives used and RAID configuration.

Hardware Specs

Software Specs

Hardware Specifications
CPU
CPU	CPU Model	AMD Ryzen V1500B
	CPU Quantity	1
	CPU Cores	4
	CPU Threads	8
	CPU Architecture	64-bit
	CPU Frequency	2.2 GHz
	Hardware Encryption Engine
Memory
Memory	System Memory	4 GB DDR4 ECC SODIMM
	Total Memory Slots	2
	Maximum Memory Capacity	32 GB (16 GB x 2)
	Notes	Synology may revise pre-installed memory module specifications in response to component lifecycle and supply conditions. All revised components undergo the same rigorous validation to ensure equivalent compatibility, stability, and 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 multi-module memory configurations, all modules must be identical and share the same model number. Check the Product Manual of your Synology product for recommended memory configurations.
Storage
Storage	Drive Bays	8
	Maximum Drive Bays with Expansion Unit	18 (DX517 x 2)
	M.2 Drive Slots	2 (NVMe)
	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.
External Ports
External Ports	RJ-45 1GbE LAN Port	4
	USB 3.2 Gen 1 Port	4
	Expansion Port	2
	Expansion Port Type	eSATA
PCIe
PCIe	PCIe Expansion	1 x Gen3 x8 slot (x4 link)
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 watts
	AC Input Power Voltage	100V to 240V AC
	Power Frequency	50/60 Hz, Single Phase
	Power Consumption	59.8 watts (Access) 26.18 watts (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)
	Operating Humidity	8% to 80% RH
	Storage Humidity	5% to 95% RH
Certification
Certification	FCC CE BSMI VCCI RCM EAC CCC KC BIS
Warranty
Warranty	2 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	DDR4 ECC SODIMM: D4ES01-4G/D4ES01-8G/D4ES03-16G Expansion Units: DX517 Enterprise Series 3.5" SATA HDD: HAT5300 Series Plus Series 3.5" SATA HDD: HAT3300 Series Enterprise Series 2.5" SATA SSD: SAT5200 Series Enterprise Series M.2 2280 NVMe SSD: SNV3400 & SNV5400 Series 25GbE Network Interface Card: E25G30-F2 10GbE Network Interface Card: E10G30-F2/E10G30-T2/E10G18-T1
	Notes	All memory modules will operate at the maximum frequency specified by the CPU manufacturer.

DSM Specifications
Storage Management
Storage Management	Maximum Single Volume Size	108 TB
	Maximum Internal Volume Number	64
	M.2 SSD Storage Pool Support*
	SSD Read/Write Cache (Determining cache size)
	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	Each internal volume (may consist of multiple drives) is expandable up to 108TB. Actual maximum storage pool and volume sizes depend on drive sizes used, the number of drive bays available, and the RAID configuration. 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. 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)
File System
File System	Internal Drives	Btrfs ext4
	External Drives	Btrfs ext4 ext3 FAT32 NTFS HFS+ exFAT
File Services
File Services	File Protocol	SMB AFP NFS FTP WebDAV Rsync
	Maximum Number of SMB Connections (FSCT-Based)	60
	Windows Access Control List (ACL) Integration
	NFS Kerberos Authentication
	Notes	Connection value of this model is tested with Synology SATA HDD fully populated and all onboard network ports Models with expandable memory are tested with the maximum supported quantity installed. SMB performance was evaluated using Microsoft File Server Capacity Tool (FSCT) version 1.3, with the following configuration: Test workload: HomeFolder scenario provided by the FSCT tool Test duration: 600 seconds Domain controller & FSCT controller: Windows Server 2022 FSCT clients: 8 × Windows 10 machines SMB feature: Directory leasing enabled
Account & Shared Folder
Account & Shared Folder	Maximum Local User Accounts	1,024
	Maximum Local Groups	256
	Maximum Shared Folder	256
	Maximum Shared Folder Sync Tasks	8
Hybrid Share
Hybrid Share	Maximum Hybrid Share Folders	10
Hyper Backup
Hyper Backup	Folder and Package Backup
	Entire System Backup
	Notes	Full-system backup requires DSM 7.2 or later.
High Availability
High Availability	Synology High Availability
Log Center
Log Center	Syslog Events per Second	1,000
Virtualization
Virtualization	VMware vSphere	ESXi 8.0 U2, ESXi 8.0 U1, ESXi 8.0, ESXi 7.0 U3, ESXi 7.0 U2, ESXi 7.0 U1, ESXi 7.0, ESXi 6.7 U3, ESXi 6.7 U2, ESXi 6.7 U1, ESXi 6.7, ESXi 6.5 U3, ESXi 6.5 U2, ESXi 6.5 U1, ESXi 6.5
	Microsoft Hyper-V	Windows Server 2022, Windows Server 2019, Windows Server 2016
	Citrix XenServer	XenServer 8, Citrix Hypervisor 8.2 LTSR CU1
	OpenStack	Cinder
General Specifications
General Specifications	Supported Protocols	SMB1 (CIFS), SMB2, SMB3, NFSv3, NFSv4, NFSv4.1, NFS Kerberized sessions, iSCSI, HTTP, HTTPs, FTP, SNMP, LDAP, CalDAV
	Supported Browsers	Chrome Firefox 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.
Add-on Packages view the complete package list
Central Management System
Central Management System
Synology AI Console
Synology AI Console	Third-Party AI Model Integration
	Maximum De-Identification Rate	60 words per second
	Notes	De-identification performance measurement: Filters for Credit Card Numbers, IBAN, Individual Taxpayer Identification Number, SSN, and Names applied to a 4,355-word English text. To enable de-identification, your device must have at least 8 GB of memory and Container Manager installed.
Synology Chat
Synology Chat	Maximum Number of Users	150
	Notes	Measured with simulated users, each with an average record of 20,000 messages, emojis, or stickers. The required server response time is below ten seconds. Models with expandable memory are tested with the maximum supported quantity installed.
Download Station
Download Station	Maximum Concurrent Download Tasks	80
SAN Manager
SAN Manager	Maximum iSCSI Target Number	64
	Maximum LUN	128
	LUN Clone/Snapshot, Windows ODX
Synology MailPlus / MailPlus Server
Synology MailPlus / MailPlus Server	Free Email Accounts	5 (Additional accounts require purchase of licenses)
	Maximum Number of Users	130
	Notes	The suggested maximum number of users is based on the following workload: 20% of users with a 20,000 item mailbox randomly performing actions and receiving 240 emails per day, and 80% of users receiving 20 emails per day. Learn more Models with SSD support are tested with a single SSD volume. Models with expandable memory are tested with the maximum supported quantity installed. Learn more about memory requirements. Operating in high-availability mode will incur additional overhead. Features enabled during evaluation: anti-spam, anti-virus, DNSBL, greylist, content scanning, and full-text search (English).
Media Server
Media Server	DLNA Compliance
Synology Photos
Synology Photos	Facial Recognition
	Object Recognition
Snapshot Replication
Snapshot Replication	Maximum Snapshots per Shared Folder	256
	Maximum Snapshots per LUN	64
	Maximum Snapshots per System	4,096
	Maximum Replication Tasks for Shared Folders	32
	Maximum Replication Tasks for LUNs	16
	Maximum Replication Tasks per System	32
Surveillance Station
Surveillance Station	Default Licenses	2 (Additional cameras require purchase of licenses)
	Maximum IP Cameras and Total FPS (H.264)	1080p: 40 channels, 1050 FPS 3M: 40 channels, 600 FPS 5M: 40 channels, 440 FPS 4K: 32 channels, 320 FPS
	Maximum IP Cameras and Total FPS (H.265)	1080p: 40 channels, 1200 FPS 3M: 40 channels, 1120 FPS 5M: 40 channels, 600 FPS 4K: 40 channels, 480 FPS
	Notes	Performance figures are obtained from testing conducted with the device fully populated with drives, with their default memory configuration, and under a continuous recording setup. Actual system capabilities may vary based on configuration, drive performance, enabled features, and the presence of additional workloads. Use NVR Selector to quickly find a suitable model based on your requirements. The number of video channels that can be viewed simultaneously is double the maximum number of cameras for the same codec and resolution.
Synology Drive
Synology Drive	Maximum Number of Users	110
	Maximum Number of Hosted Files	1,000,000 (applies to files indexed or hosted by Synology Drive. For file access through other standard protocols, refer to the File Services section above)
	Notes	The suggested maximum number of users is based on the following workload: 20% of users randomly perform file operations (upload, download, move, and delete), and 80% of users are logged in but idle. Learn more Models with SSD support are tested with a single SSD volume. Models with expandable memory are tested with the maximum supported quantity installed. 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 Number of Users	110
	Notes	The suggested maximum number of users is based on the following workload: 20% of users are executing random actions at an average of 30-second intervals, and 80% of users are logged in and viewing a file. Learn more Models with SSD support are tested with a single SSD volume. Models with expandable memory are tested with the maximum supported quantity installed. Client performance may affect maximum simultaneous editing users. Client PCs used for testing: Intel Core i3-3220 / 8GB RAM
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	8

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 specifications above, please contact our regional partners for professional advice.