Keep services online with efficient high-availability storage

Accessible and convenient

Accessible and convenient

Maintain data availability with an active-passive high availability dual-controller module

Versatile applications

Versatile applications

Manage, distribute, and protect data, back up endpoints, and guard physical premises

Fast and efficient

Fast and efficient

Over 3,500/2,900 MB/s seq. read/write throughput1 and over 500 TB maximum storage capacity2

Built-in High Availability

Keep file sharing services, block storage, backups, and other office applications online with automatic minute-level failover. Defend against operational disruptions with two independent and hot-swappable controllers operating in an active-passive configuration.

Minute-level automatic failover Real-time workload protection

Made for demanding environments

The SA3400D is engineered to provide outstanding performance in both NAS and SAN storage roles. Its throughput and random I/O performance support efficient SMB and NFS file serving as well as a range of iSCSI and Fibre Channel block storage applications.

Consolidate your data infrastructure

Manage, protect, and share data with versatile business solutions. Empower team collaboration, sandbox applications, and provide VM storage on a unified platform.

Private cloud management

Efficient and secure folder sharing
Efficient cross-site file syncing
Efficient and secure folder sharing
Efficient cross-site file syncing

Built-in data protection

Back up PCs, servers, SaaS accounts, and VMs
Create off-site backups for shared folders, LUNs, and more
Back up PCs, servers, SaaS accounts, and VMs
Create off-site backups for shared folders, LUNs, and more

Business productivity solutions

Boost team productivity with collaborative tools
Sandbox and instantly restore critical services
Supports industry-leading virtualization platforms
Boost team productivity with collaborative tools
Sandbox and instantly restore critical services
Supports industry-leading virtualization platforms

Flexible options to meet changing needs

Flexibly scale storage capacity, optimize I/O performance, and meet different network needs with a range of expansion options.6

Add storage capacity on demand

Scale server capacity up to 576 TB7 when your data storage needs increase by adding two 12-bay RXD1219sas expansion units.

Boost network and I/O performance

Add 10/25GbE connectivity with optional add-in cards.8 Create all-flash storage volumes with SAS SSD for lightening-fast I/O, or boost IOPS and cut down latency on HDD volumes by creating SAS SSD read/write cache volumes.9

Up to
576 TB
raw capacity
Up to
Up to
218/92K IOPS
read/write with SSD cache

Performance backed by Synology drives

Engineered to handle intensive workloads, Synology hard drives consistently deliver top-grade performance.

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Synology has you covered

Synology has you covered

The SA3400D is backed by Synology's 5-year limited warranty,10 including technical support and hardware replacement services to maximize your return on investment and ensure continuous, high-quality performance. Learn more


productSA3400Dfront view photo
productSA3400Dback view photo
  • 1Power Button and Indicator
  • 2High Availability Status Indicator
  • 3Alert Indicator
  • 4Mute Button
  • 5Drive Status Indicators
  • 6Drive Trays
  • 7Rail Kit Release Tabs
  • 8Power Ports
  • 9PSU Indicators
  • 10PSU Fans
  • 11PCI Express Expansion Slots
  • 12Console Ports
  • 131GbE RJ-45 Ports
  • 1410GbE RJ-45 Ports
  • 15Expansion Ports
  • 16Reset Buttons
  • 17Remove Indicators
  • 18Alert Indicators
  • 19Status Indicators
  • 20Power Indicators


  1. Performance figures are obtained through internal testing by Synology. Actual performance may vary depending on the testing environment, usage, and configuration. See performance charts for more information.

  2. Volumes up to 108 TB are supported with the default installed memory. Volumes up to 200 TB can be created if the memory is upgraded to 32 GB. Learn more about maximum volume sizes.

  3. C2 Storage for Hyper Backup and Hybrid Share requires purchase of an annual or monthly subscription. A free trial is available for each newly registered device.

  4. Five MailPlus email accounts are included. Additional email accounts can be added with the purchase of Synology MailPlus License Packs.  Learn more

  5. Certain advanced features require Virtual Machine Manager Pro. One Virtual DSM license is included. Additional Virtual DSM instances require the purchase of Virtual DSM Licenses.

  6. Please refer to the SA3400D compatibility list for the latest optional accessories lists.

  7. The SA3400D supports up to 36 drives with two Synology RXD1219sas expansion units, sold separately.

  8. For the most up-to-date list of compatible NICs and HBAs, please check our compatibility list.

  9. SSD cache volumes store frequently accessed data from conventional HDD volumes to reduce I/O latency and improve system performance. To find out which SAS SSDs are supported, please check our compatibility list.

  10. The warranty period starts from the date of purchase as stated on your purchase receipt. Learn more about our limited product warranty policy.

Hardware Specifications
Number of Controller Module 2
CPU Model Intel Xeon D-1541
CPU Quantity 1 (per controller)
CPU Architecture 64-bit
CPU Frequency 8-core 2.1 (base) / 2.7 (turbo) GHz
Hardware Encryption Engine (AES-NI)
System Memory 8 GB DDR4 ECC UDIMM (per controller)
Memory Module Pre-installed 8 GB (8 GB x 1) (per controller)
Total Memory Slots 4 (per controller)
Maximum Memory Capacity 64 GB (16 GB x 4) (per controller)
  • 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.
  • Installing memory modules with differing capacities is not recommended. Check the Hardware Installation Guide of your Synology product for recommended memory configurations.
Drive Bays 12
Maximum Drive Bays with Expansion Unit 36 (RXD1219sas x 2)
Compatible Drive Type* (See all supported drives)
  • 3.5” dual-port SAS HDD
  • 2.5” dual-port SAS SSD
Hot Swappable Drive*
  • 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.
  • "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 2 (with Link Aggregation / Failover support) (per controller)
RJ-45 10GbE LAN Port 1 (per controller)
Expansion Port 1
Notes This device's 1GbE LAN ports have a maximum transmission unit (MTU) size of 1,500 bytes.
PCIe Expansion 1 x Gen3 x8 slot (x8 link) (per controller)
Form Factor (RU) 2U
Size (Height x Width x Depth) 88 mm x 482 mm x 724 mm
Weight 19.7 kg
Rack Installation Support* 4-post 19" rack (Synology Rail Kit - RKS-02)
Notes The rail kit is sold separately
System Fan 60 mm x 60 mm x 2 pcs
Fan Speed Mode
  • Full-Speed Mode
  • Cool Mode
  • Quiet Mode
Easy Replacement System Fan
Power Recovery
Noise Level* 51.3 dB(A)
Power Supply Unit / Adapter 500 W
Redundant Power Supply
AC Input Power Voltage 100V to 240V AC
Power Frequency 50/60 Hz, Single Phase
Power Consumption 257.78 W (Access)
British Thermal Unit 879.58 BTU/hr (Access)
  • Power consumption is measured when it is fully loaded with Synology 12TB HAS5300-12T hard drive(s).
  • Noise Level Testing Environment: Fully loaded with Synology HAS5300-8T 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%
Operating Temperature 0°C to 35°C (32°F to 95°F)
Storage Temperature -20°C to 60°C (-5°F to 140°F)
Relative Humidity 5% to 95% RH
  • FCC
  • CE
  • BSMI
  • VCCI
  • UKCA
  • EAC
  • CCC
  • KC
  • RCM
5 Years
Notes The warranty period starts from the purchase date as stated on your purchase receipt. (Learn more)
RoHS Compliant
Packaging Content
Packaging Content
  • Main Unit X 1
  • Accessory Pack X 1
  • AC Power Cord X 2
  • Quick Installation Guide X 1
Optional Accessories
Optional Accessories
Notes Installing memory modules with differing capacities is not recommended. Check the Hardware Installation Guide of your Synology product for recommended memory configurations.
DSM Specifications
Maximum Single Volume Size
  • 200 TB (32 GB memory required)
  • 108 TB
Maximum Internal Volume Number 64
SSD Read / Write Cache (White Paper)
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
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
  • 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.
  • Volumes over 108 TB require 32 GB of memory or more.
Internal Drives
  • Btrfs
  • ext4
File Protocol
  • SMB
  • AFP
  • NFS
  • FTP
  • WebDAV
  • Rsync
Maximum Concurrent SMB/AFP/FTP Connections 1,200
Maximum Concurrent SMB/AFP/FTP Connections (with RAM expansion) 6,000
Windows Access Control List (ACL) Integration
NFS Kerberos Authentication
  • 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.
  • 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 16,000
Maximum Local Groups 512
Maximum Shared Folder 512
Maximum Shared Folder Sync Tasks 32
Maximum Hybrid Share Folders 30
Folder and Package Backup
Entire System Backup
Notes Full-system backup requires DSM 7.2 or later.
Synology High Availability
Notes Synology High Availability is a built-in package for SA3400D to maximize service uptime. SA3400D does not support forming a high-availability cluster with another server unit.
Syslog Events per Second 3,000
VMware ESXi 6.5 and VAAI
Windows Server 2022
Citrix Ready
Supported Protocols 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
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)
Suggested Concurrent Users 500
  • 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.
  • When applicable, systems are tested configured with maximum memory and set to allow the maximum number of connections.
Maximum iSCSI Target Number 256
Maximum LUN 512
LUN Clone/Snapshot, Windows ODX
Free Email Accounts 5 (Additional accounts require purchase of licenses)
Suggested Maximum Users 10,000
Suggested Concurrent Users 2,000
Maximum Server Performance 4,312,000 emails per day, approx. 131 GB
  • 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).
Maximum Snapshots per Shared Folder 1,024
Maximum of System Snapshots 65,536
Default Licenses 2 (Additional cameras require purchase of licenses)
Maximum IP Cameras and Total FPS (H.264)
  • 720p: 180 channels, 5400 FPS
  • 1080p: 100 channels, 2800 FPS
  • 3M: 100 channels, 1500 FPS
  • 5M: 90 channels, 900 FPS
  • 4K: 55 channels, 550 FPS
Maximum IP Cameras and Total FPS (H.265)
  • 720p: 300 channels, 9000 FPS
  • 1080p: 200 channels, 4000 FPS
  • 3M: 100 channels, 2400 FPS
  • 5M: 100 channels, 1500 FPS
  • 4K: 100 channels, 1080 FPS
  • Surveillance Station 9.1.3 or above is required to support the maximum IP cameras and FPS figures listed.
  • Performance figures are obtained from testing conducted with the device fully populated with drives 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.
Recommended Number of Concurrent Sync Clients 2,000 (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)
  • 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.
Suggested Maximum Users 12,500
Suggested Concurrent Users 5,000
  • 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 16 (Learn more)
Recommended Virtual DSM Number (Licenses required) 16 (including 1 Free License)
Notes The specifications vary depending on system configuration and memory size.
Maximum Connections 60


  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.