1. products list

Comparison results

DS1821+ DS1823xs+
DS1821+ DS1823xs+
Hardware Specs
Hardware Specifications
CPU
CPU Model AMD Ryzen V1500B AMD Ryzen V1780B
CPU Quantity 1 1
CPU Core 4 4
CPU Architecture 64-bit 64-bit
CPU Frequency 2.2 GHz 3.35 (base) / 3.6 (turbo) GHz
Hardware Encryption Engine
Memory
System Memory 4 GB DDR4 ECC SODIMM 8 GB DDR4 ECC SODIMM
Memory Module Pre-installed 4 GB (4 GB x 1) 8 GB (8 GB x 1)
Total Memory Slots 2 2
Maximum Memory Capacity 32 GB (16 GB x 2) 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 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.
  • 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 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
Drive Bays 8 8
Maximum Drive Bays with Expansion Unit 18 (DX517 x 2) 18 (DX517 x 2)
M.2 Drive Slots 2 (NVMe) 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
  • 3.5" 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.
  • The hot swappable drive feature is not supported by M.2 SSD slots.
  • Synology only guarantees full functionality, reliability, and performance for Synology drives listed on the compatibility list. The use of non-validated components may limit certain functionality and result in data loss and system instability.
External Ports
RJ-45 1GbE LAN Port 4 2
RJ-45 10GbE LAN Port 1
Out-of-Band Management LAN Port 1
USB 3.2 Gen 1 Port 4 3
Expansion Port 2 2
Expansion Port Type eSATA eSATA
Notes MTU value of 1GbE LAN port has a limit of 1500.
PCIe
PCIe Expansion 1 x Gen3 x8 slot (x4 link) 1 x Gen3 x8 slot (x4 link)
Appearance
Size (Height x Width x Depth) 166 mm x 343 mm x 243 mm 166 mm x 343 mm x 243 mm
Weight 6 kg 6.2 kg
Others
System Fan 120 mm x 120 mm x 2 pcs 120 mm x 120 mm x 2 pcs
Fan Speed Mode
  • Full-Speed Mode
  • Cool Mode
  • Quiet 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) 23.6 dB(A)
Scheduled Power On / Off
Wake on LAN / WAN
Power Supply Unit / Adapter 250 watts 250 watts
AC Input Power Voltage 100V to 240V AC 100V to 240V AC
Power Frequency 50/60 Hz, Single Phase 50/60 Hz, Single Phase
Power Consumption* 59.8 watts (Access)
26.18 watts (HDD Hibernation)		 87.93 watts (Access)
28.37 watts (HDD Hibernation)
British Thermal Unit 204.05 BTU/hr (Access)
89.33 BTU/hr (HDD Hibernation)		 300.23 BTU/hr (Access)
96.87 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%
  • For more information on how power consumption is measured, refer to this article.
  • Noise testing was conducted with the Synology system fully installed with Synology SATA HDDs and in an idle state. Two G.R.A.S. Type 40AE microphones are placed at a 1 m distance from the front and rear of the device. Background noise: 16.49-17.51 dB(A); Temperature: 24.25-25.75˚C; Humidity: 58.2-61.8%
Temperature
Operating Temperature 0°C to 40°C (32°F to 104°F) 0°C to 40°C (32°F to 104°F)
Storage Temperature -20°C to 60°C (-5°F to 140°F) -20°C to 60°C (-5°F to 140°F)
Relative Humidity 5% to 95% RH 5% to 95% RH
Certification
  • FCC
  • CE
  • BSMI
  • VCCI
  • RCM
  • EAC
  • CCC
  • KC
  • BIS
  • FCC
  • CE
  • BSMI
  • VCCI
  • RCM
  • EAC
  • CCC
  • KC
  • BIS
Warranty 3-year hardware warranty, extendable to 5 years with EW201 5 Years
Notes
  • The warranty period starts from the purchase date as stated on your purchase receipt. (Learn more)
  • EW201/EW202 is only available in Asia, Africa, and Oceania. Refer to the Extended Warranty website for details on supported countries/regions. (Learn more)
 The warranty period starts from the purchase date as stated on your purchase receipt. (Learn more)
Environment RoHS Compliant RoHS Compliant
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
  • 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
Notes All memory modules will operate at the maximum frequency specified by the CPU manufacturer.
Software Specs
DSM Specifications
Storage Management
Maximum Single Volume Size 108 TB
  • 200 TB (32 GB memory required)
  • 108 TB
Maximum Internal Volume Number 64 256
M.2 SSD Storage Pool Support*
SSD Read/Write Cache (Determining cache size)
SSD TRIM
RAID Group
Supported RAID Type
  • Synology Hybrid RAID
  • Basic
  • JBOD
  • RAID 0
  • RAID 1
  • RAID 5
  • RAID 6
  • RAID 10
  • 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
  • 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
  • RAID F1
  • RAID 1
  • RAID 5
  • RAID 6
  • RAID 10
Volume Expansion by Adding a HDD
  • Synology Hybrid RAID
  • JBOD
  • RAID 5
  • RAID 6
  • RAID F1
  • JBOD
  • RAID 5
  • RAID 6
Global Hot Spare Supported RAID Type
  • Synology Hybrid RAID
  • RAID 1
  • RAID 5
  • RAID 6
  • RAID 10
  • RAID F1
  • 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)
  • Volumes over 108 TB require 32 GB of memory or 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.
  • 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
Internal Drives
  • Btrfs
  • ext4
  • Btrfs
  • ext4
External Drives
  • Btrfs
  • ext4
  • ext3
  • FAT32
  • NTFS
  • HFS+
  • exFAT
  • Btrfs
  • ext4
  • ext3
  • FAT32
  • NTFS
  • HFS+
  • exFAT
File Services
File Protocol
  • SMB
  • AFP
  • NFS
  • FTP
  • WebDAV
  • Rsync
  • SMB
  • AFP
  • NFS
  • FTP
  • WebDAV
  • Rsync
Maximum Number of SMB Connections (FSCT-Based) with RAM Expansion 60 340
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
  • The testing standard was based on client computers running Windows Server 2022 and Microsoft File Server Capacity Tool (FSCT).
  • Connection value of this model is tested with Synology SATA SSD fully populated and up to four 10GbE network ports
  • The testing standard was based on client computers running Windows Server 2022 and Microsoft File Server Capacity Tool (FSCT).
Account & Shared Folder
Maximum Local User Accounts 1,024 2,048
Maximum Local Groups 256 512
Maximum Shared Folder 256 512
Maximum Shared Folder Sync Tasks 8 12
Hybrid Share
Hybrid Share Folder Number 10 15
Hyper Backup
Data & Folder Backup
Entire System Backup
Notes Full-system backup requires DSM 7.2 or later. Full-system backup requires DSM 7.2 or later.
High Availability
Synology High Availability
Log Center
Syslog Events per Second 1,000 3,000
Virtualization
VMware ESXi 6.5 and VAAI
Windows Server 2016
Windows Server 2019
Windows Server 2022
Citrix Ready
OpenStack
General Specifications
Supported Protocols SMB1 (CIFS), SMB2, SMB3, NFSv3, NFSv4, NFSv4.1, NFS Kerberized sessions, iSCSI, HTTP, HTTPs, FTP, SNMP, LDAP, CalDAV SMB1 (CIFS), SMB2, SMB3, NFSv3, NFSv4, NFSv4.1, NFS Kerberized sessions, iSCSI, Fibre Channel, HTTP, HTTPs, FTP, SNMP, LDAP, CalDAV
Supported Browsers
  • Chrome
  • Firefox
  • Edge
  • Safari
  • 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 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. For an updated list of supported browser versions, check the DSM Technical Specifications.
Add-on Packages (view the complete package list)
Central Management System
Synology Chat
Maximum Number of Users 150 400
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.
  • 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
Maximum Concurrent Download Tasks 80 80
SAN Manager
Maximum iSCSI Target Number 64 64
Maximum LUN 128 128
LUN Clone/Snapshot, Windows ODX
Synology MailPlus / MailPlus Server
Free Email Accounts 5 (Additional accounts require purchase of licenses) 5 (Additional accounts require purchase of licenses)
Maximum Number of Users 130 710
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).
  • 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
DLNA Compliance
Synology Photos
Facial Recognition
Object Recognition
Snapshot Replication
Maximum Snapshots per Shared Folder 256 256
Maximum of System Snapshots 4,096 4,096
Surveillance Station
Default Licenses 2 (Additional cameras require purchase of licenses) 2 (Additional cameras require purchase of licenses)
Suggested 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
  • 1080p: 75 channels, 2100 FPS
  • 3M: 75 channels, 1500 FPS
  • 5M: 75 channels, 900 FPS
  • 4K: 55 channels, 550 FPS
Suggested 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
  • 1080p: 75 channels, 2250 FPS
  • 3M: 75 channels, 2250 FPS
  • 5M: 75 channels, 1500 FPS
  • 4K: 75 channels, 900 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 streams that can be viewed simultaneously is twice the suggested maximum number of cameras. For example, if the suggested maximum number of cameras for a model is 10 under H.264, 1080p, the model can support up to 20 streams of the same specification at the same time.
  • 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 streams that can be viewed simultaneously is twice the suggested maximum number of cameras. For example, if the suggested maximum number of cameras for a model is 10 under H.264, 1080p, the model can support up to 20 streams of the same specification at the same time.
Synology Drive
Maximum Number of Users 110 610
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) 5,000,000 (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.
  • 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
Maximum Number of Users 110 590
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
  • 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
Recommended Virtual Machine Instances 8 (Learn more) 8 (Learn more)
Recommended Virtual DSM Number (Licenses required) 8 (including 1 Free License) 8 (including 1 Free License)
Notes The specifications vary depending on system configuration and memory size. The specifications vary depending on system configuration and memory size.
VPN Server
Maximum Connections 8 12
Hardware Specs
Hardware Specifications
CPU
CPU Model
DS1821+ AMD Ryzen V1500B
DS1823xs+ AMD Ryzen V1780B
CPU Quantity
DS1821+ 1
DS1823xs+ 1
CPU Core
DS1821+ 4
DS1823xs+ 4
CPU Architecture
DS1821+ 64-bit
DS1823xs+ 64-bit
CPU Frequency
DS1821+ 2.2 GHz
DS1823xs+ 3.35 (base) / 3.6 (turbo) GHz
Hardware Encryption Engine
DS1821+
DS1823xs+
Memory
System Memory
DS1821+ 4 GB DDR4 ECC SODIMM
DS1823xs+ 8 GB DDR4 ECC SODIMM
Memory Module Pre-installed
DS1821+ 4 GB (4 GB x 1)
DS1823xs+ 8 GB (8 GB x 1)
Total Memory Slots
DS1821+ 2
DS1823xs+ 2
Maximum Memory Capacity
DS1821+ 32 GB (16 GB x 2)
DS1823xs+ 32 GB (16 GB x 2)
Notes
DS1821+
  • 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 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.
DS1823xs+
  • 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 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
Drive Bays
DS1821+ 8
DS1823xs+ 8
Maximum Drive Bays with Expansion Unit
DS1821+ 18 (DX517 x 2)
DS1823xs+ 18 (DX517 x 2)
M.2 Drive Slots
DS1821+ 2 (NVMe)
DS1823xs+ 2 (NVMe)
Drive Type (See all supported drives)
DS1821+
  • 3.5" SATA HDD
  • 2.5" SATA HDD
  • 2.5" SATA SSD
  • M.2 2280 NVMe SSD
DS1823xs+
  • 3.5" SATA HDD
  • 2.5" SATA SSD
  • M.2 2280 NVMe SSD
Hot Swappable Drive*
DS1821+
DS1823xs+
Notes
DS1821+ The hot swappable drive feature is not supported by M.2 SSD slots.
DS1823xs+
  • The hot swappable drive feature is not supported by M.2 SSD slots.
  • Synology only guarantees full functionality, reliability, and performance for Synology drives listed on the compatibility list. The use of non-validated components may limit certain functionality and result in data loss and system instability.
External Ports
RJ-45 1GbE LAN Port
DS1821+ 4
DS1823xs+ 2
RJ-45 10GbE LAN Port
DS1821+
DS1823xs+ 1
Out-of-Band Management LAN Port
DS1821+
DS1823xs+ 1
USB 3.2 Gen 1 Port
DS1821+ 4
DS1823xs+ 3
Expansion Port
DS1821+ 2
DS1823xs+ 2
Expansion Port Type
DS1821+ eSATA
DS1823xs+ eSATA
Notes
DS1821+
DS1823xs+ MTU value of 1GbE LAN port has a limit of 1500.
PCIe
PCIe Expansion
DS1821+ 1 x Gen3 x8 slot (x4 link)
DS1823xs+ 1 x Gen3 x8 slot (x4 link)
Appearance
Size (Height x Width x Depth)
DS1821+ 166 mm x 343 mm x 243 mm
DS1823xs+ 166 mm x 343 mm x 243 mm
Weight
DS1821+ 6 kg
DS1823xs+ 6.2 kg
Others
System Fan
DS1821+ 120 mm x 120 mm x 2 pcs
DS1823xs+ 120 mm x 120 mm x 2 pcs
Fan Speed Mode
DS1821+
  • Full-Speed Mode
  • Cool Mode
  • Quiet Mode
DS1823xs+
  • Full-Speed Mode
  • Cool Mode
  • Quiet Mode
Easy Replacement System Fan
DS1821+
DS1823xs+
Brightness Adjustable Front LED Indicators
DS1821+
DS1823xs+
Power Recovery
DS1821+
DS1823xs+
Noise Level*
DS1821+ 22.2 dB(A)
DS1823xs+ 23.6 dB(A)
Scheduled Power On / Off
DS1821+
DS1823xs+
Wake on LAN / WAN
DS1821+
DS1823xs+
Power Supply Unit / Adapter
DS1821+ 250 watts
DS1823xs+ 250 watts
AC Input Power Voltage
DS1821+ 100V to 240V AC
DS1823xs+ 100V to 240V AC
Power Frequency
DS1821+ 50/60 Hz, Single Phase
DS1823xs+ 50/60 Hz, Single Phase
Power Consumption*
DS1821+ 59.8 watts (Access)
26.18 watts (HDD Hibernation)
DS1823xs+ 87.93 watts (Access)
28.37 watts (HDD Hibernation)
British Thermal Unit
DS1821+ 204.05 BTU/hr (Access)
89.33 BTU/hr (HDD Hibernation)
DS1823xs+ 300.23 BTU/hr (Access)
96.87 BTU/hr (HDD Hibernation)
Notes
DS1821+
  • 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%
DS1823xs+
  • For more information on how power consumption is measured, refer to this article.
  • Noise testing was conducted with the Synology system fully installed with Synology SATA HDDs and in an idle state. Two G.R.A.S. Type 40AE microphones are placed at a 1 m distance from the front and rear of the device. Background noise: 16.49-17.51 dB(A); Temperature: 24.25-25.75˚C; Humidity: 58.2-61.8%
Temperature
Operating Temperature
DS1821+ 0°C to 40°C (32°F to 104°F)
DS1823xs+ 0°C to 40°C (32°F to 104°F)
Storage Temperature
DS1821+ -20°C to 60°C (-5°F to 140°F)
DS1823xs+ -20°C to 60°C (-5°F to 140°F)
Relative Humidity
DS1821+ 5% to 95% RH
DS1823xs+ 5% to 95% RH
Certification
DS1821+
  • FCC
  • CE
  • BSMI
  • VCCI
  • RCM
  • EAC
  • CCC
  • KC
  • BIS
DS1823xs+
  • FCC
  • CE
  • BSMI
  • VCCI
  • RCM
  • EAC
  • CCC
  • KC
  • BIS
Warranty
DS1821+ 3-year hardware warranty, extendable to 5 years with EW201
DS1823xs+ 5 Years
Notes
DS1821+
  • The warranty period starts from the purchase date as stated on your purchase receipt. (Learn more)
  • EW201/EW202 is only available in Asia, Africa, and Oceania. Refer to the Extended Warranty website for details on supported countries/regions. (Learn more)
DS1823xs+ The warranty period starts from the purchase date as stated on your purchase receipt. (Learn more)
Environment
DS1821+ RoHS Compliant
DS1823xs+ RoHS Compliant
Packaging Content
DS1821+
  • Main Unit X 1
  • Accessory Pack X 1
  • AC Power Cord X 1
  • RJ-45 LAN Cable X 2
  • Quick Installation Guide X 1
DS1823xs+
  • 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
DS1821+
DS1823xs+
Notes
DS1821+ All memory modules will operate at the maximum frequency specified by the CPU manufacturer.
DS1823xs+
Software Specs
DSM Specifications
Storage Management
Maximum Single Volume Size
DS1821+ 108 TB
DS1823xs+
  • 200 TB (32 GB memory required)
  • 108 TB
Maximum Internal Volume Number
DS1821+ 64
DS1823xs+ 256
M.2 SSD Storage Pool Support*
DS1821+
DS1823xs+
SSD Read/Write Cache (Determining cache size)
DS1821+
DS1823xs+
SSD TRIM
DS1821+
DS1823xs+
RAID Group
DS1821+
DS1823xs+
Supported RAID Type
DS1821+
  • Synology Hybrid RAID
  • Basic
  • JBOD
  • RAID 0
  • RAID 1
  • RAID 5
  • RAID 6
  • RAID 10
DS1823xs+
  • RAID F1
  • Basic
  • JBOD
  • RAID 0
  • RAID 1
  • RAID 5
  • RAID 6
  • RAID 10
RAID Migration
DS1821+
  • Basic to RAID 1
  • Basic to RAID 5
  • RAID 1 to RAID 5
  • RAID 5 to RAID 6
DS1823xs+
  • Basic to RAID 1
  • Basic to RAID 5
  • RAID 1 to RAID 5
  • RAID 5 to RAID 6
Volume Expansion with Larger HDDs
DS1821+
  • Synology Hybrid RAID
  • RAID 1
  • RAID 5
  • RAID 6
  • RAID 10
DS1823xs+
  • RAID F1
  • RAID 1
  • RAID 5
  • RAID 6
  • RAID 10
Volume Expansion by Adding a HDD
DS1821+
  • Synology Hybrid RAID
  • JBOD
  • RAID 5
  • RAID 6
DS1823xs+
  • RAID F1
  • JBOD
  • RAID 5
  • RAID 6
Global Hot Spare Supported RAID Type
DS1821+
  • Synology Hybrid RAID
  • RAID 1
  • RAID 5
  • RAID 6
  • RAID 10
DS1823xs+
  • RAID F1
  • RAID 1
  • RAID 5
  • RAID 6
  • RAID 10
Notes
DS1821+
  • 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)
DS1823xs+
  • Volumes over 108 TB require 32 GB of memory or 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.
  • 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
Internal Drives
DS1821+
  • Btrfs
  • ext4
DS1823xs+
  • Btrfs
  • ext4
External Drives
DS1821+
  • Btrfs
  • ext4
  • ext3
  • FAT32
  • NTFS
  • HFS+
  • exFAT
DS1823xs+
  • Btrfs
  • ext4
  • ext3
  • FAT32
  • NTFS
  • HFS+
  • exFAT
File Services
File Protocol
DS1821+
  • SMB
  • AFP
  • NFS
  • FTP
  • WebDAV
  • Rsync
DS1823xs+
  • SMB
  • AFP
  • NFS
  • FTP
  • WebDAV
  • Rsync
Maximum Number of SMB Connections (FSCT-Based) with RAM Expansion
DS1821+ 60
DS1823xs+ 340
Windows Access Control List (ACL) Integration
DS1821+
DS1823xs+
NFS Kerberos Authentication
DS1821+
DS1823xs+
Notes
DS1821+
  • Connection value of this model is tested with Synology SATA HDD fully populated and all onboard network ports
  • The testing standard was based on client computers running Windows Server 2022 and Microsoft File Server Capacity Tool (FSCT).
DS1823xs+
  • Connection value of this model is tested with Synology SATA SSD fully populated and up to four 10GbE network ports
  • The testing standard was based on client computers running Windows Server 2022 and Microsoft File Server Capacity Tool (FSCT).
Account & Shared Folder
Maximum Local User Accounts
DS1821+ 1,024
DS1823xs+ 2,048
Maximum Local Groups
DS1821+ 256
DS1823xs+ 512
Maximum Shared Folder
DS1821+ 256
DS1823xs+ 512
Maximum Shared Folder Sync Tasks
DS1821+ 8
DS1823xs+ 12
Hybrid Share
Hybrid Share Folder Number
DS1821+ 10
DS1823xs+ 15
Hyper Backup
Data & Folder Backup
DS1821+
DS1823xs+
Entire System Backup
DS1821+
DS1823xs+
Notes
DS1821+ Full-system backup requires DSM 7.2 or later.
DS1823xs+ Full-system backup requires DSM 7.2 or later.
High Availability
Synology High Availability
DS1821+
DS1823xs+
Log Center
DS1821+
DS1823xs+
Syslog Events per Second
DS1821+ 1,000
DS1823xs+ 3,000
Virtualization
VMware ESXi 6.5 and VAAI
DS1821+
DS1823xs+
Windows Server 2016
DS1821+
DS1823xs+
Windows Server 2019
DS1821+
DS1823xs+
Windows Server 2022
DS1821+
DS1823xs+
Citrix Ready
DS1821+
DS1823xs+
OpenStack
DS1821+
DS1823xs+
General Specifications
Supported Protocols
DS1821+ SMB1 (CIFS), SMB2, SMB3, NFSv3, NFSv4, NFSv4.1, NFS Kerberized sessions, iSCSI, HTTP, HTTPs, FTP, SNMP, LDAP, CalDAV
DS1823xs+ SMB1 (CIFS), SMB2, SMB3, NFSv3, NFSv4, NFSv4.1, NFS Kerberized sessions, iSCSI, Fibre Channel, HTTP, HTTPs, FTP, SNMP, LDAP, CalDAV
Supported Browsers
DS1821+
  • Chrome
  • Firefox
  • Edge
  • Safari
DS1823xs+
  • Chrome
  • Firefox
  • Edge
  • Safari
Supported Language
DS1821+ 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
DS1823xs+ 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
DS1821+ For an updated list of supported browser versions, check the DSM Technical Specifications.
DS1823xs+ For an updated list of supported browser versions, check the DSM Technical Specifications.
Add-on Packages (view the complete package list)
Central Management System
DS1821+
DS1823xs+
Synology Chat
DS1821+
DS1823xs+
Maximum Number of Users
DS1821+ 150
DS1823xs+ 400
Notes
DS1821+
  • 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.
DS1823xs+
  • 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
DS1821+
DS1823xs+
Maximum Concurrent Download Tasks
DS1821+ 80
DS1823xs+ 80
SAN Manager
DS1821+
DS1823xs+
Maximum iSCSI Target Number
DS1821+ 64
DS1823xs+ 64
Maximum LUN
DS1821+ 128
DS1823xs+ 128
LUN Clone/Snapshot, Windows ODX
DS1821+
DS1823xs+
Synology MailPlus / MailPlus Server
DS1821+
DS1823xs+
Free Email Accounts
DS1821+ 5 (Additional accounts require purchase of licenses)
DS1823xs+ 5 (Additional accounts require purchase of licenses)
Maximum Number of Users
DS1821+ 130
DS1823xs+ 710
Notes
DS1821+
  • 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).
DS1823xs+
  • 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
DS1821+
DS1823xs+
DLNA Compliance
DS1821+
DS1823xs+
Synology Photos
DS1821+
DS1823xs+
Facial Recognition
DS1821+
DS1823xs+
Object Recognition
DS1821+
DS1823xs+
Snapshot Replication
DS1821+
DS1823xs+
Maximum Snapshots per Shared Folder
DS1821+ 256
DS1823xs+ 256
Maximum of System Snapshots
DS1821+ 4,096
DS1823xs+ 4,096
Surveillance Station
DS1821+
DS1823xs+
Default Licenses
DS1821+ 2 (Additional cameras require purchase of licenses)
DS1823xs+ 2 (Additional cameras require purchase of licenses)
Suggested Maximum IP Cameras and Total FPS (H.264)
DS1821+
  • 1080p: 40 channels, 1050 FPS
  • 3M: 40 channels, 600 FPS
  • 5M: 40 channels, 440 FPS
  • 4K: 32 channels, 320 FPS
DS1823xs+
  • 1080p: 75 channels, 2100 FPS
  • 3M: 75 channels, 1500 FPS
  • 5M: 75 channels, 900 FPS
  • 4K: 55 channels, 550 FPS
Suggested Maximum IP Cameras and Total FPS (H.265)
DS1821+
  • 1080p: 40 channels, 1200 FPS
  • 3M: 40 channels, 1120 FPS
  • 5M: 40 channels, 600 FPS
  • 4K: 40 channels, 480 FPS
DS1823xs+
  • 1080p: 75 channels, 2250 FPS
  • 3M: 75 channels, 2250 FPS
  • 5M: 75 channels, 1500 FPS
  • 4K: 75 channels, 900 FPS
Notes
DS1821+
  • 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 streams that can be viewed simultaneously is twice the suggested maximum number of cameras. For example, if the suggested maximum number of cameras for a model is 10 under H.264, 1080p, the model can support up to 20 streams of the same specification at the same time.
DS1823xs+
  • 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 streams that can be viewed simultaneously is twice the suggested maximum number of cameras. For example, if the suggested maximum number of cameras for a model is 10 under H.264, 1080p, the model can support up to 20 streams of the same specification at the same time.
Synology Drive
DS1821+
DS1823xs+
Maximum Number of Users
DS1821+ 110
DS1823xs+ 610
Maximum Number of Hosted Files
DS1821+ 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)
DS1823xs+ 5,000,000 (applies to files indexed or hosted by Synology Drive. For file access through other standard protocols, refer to the File Services section above)
Notes
DS1821+
  • 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.
DS1823xs+
  • 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
DS1821+
DS1823xs+
Maximum Number of Users
DS1821+ 110
DS1823xs+ 590
Notes
DS1821+
  • 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
DS1823xs+
  • 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
DS1821+
DS1823xs+
Recommended Virtual Machine Instances
DS1821+ 8 (Learn more)
DS1823xs+ 8 (Learn more)
Recommended Virtual DSM Number (Licenses required)
DS1821+ 8 (including 1 Free License)
DS1823xs+ 8 (including 1 Free License)
Notes
DS1821+ The specifications vary depending on system configuration and memory size.
DS1823xs+ The specifications vary depending on system configuration and memory size.
VPN Server
DS1821+
DS1823xs+
Maximum Connections
DS1821+ 8
DS1823xs+ 12