CPU > CPU Model Intel Xeon D-1521
CPU Quantity 1
CPU Cores 4
CPU Threads 8
CPU Architecture 64-bit
CPU Frequency 2.4 (base) / 2.7 (turbo) GHz
Memory > System Memory 8 GB DDR4 ECC UDIMM
Memory Module Pre-installed 8 GB (8 GB × 1)
Total Memory Slots 4
Maximum Memory Capacity 64 GB (16 GB × 4)
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 more information on the recommended memory configurations, visit here.
Storage > Drive Bays (See all supported drives) .bx{display:inline-block;vertical-align:middle;}.it{display:flex;}.it::before{content:'• ';white-space:pre;}.it:only-child::before{display:none;}12 × 3.5" SATA HDD or 2.5" SATA HDD/SSD
Maximum Drive Bays with Expansion Unit 36 (RX1217 × 2)
External Ports > RJ-45 1GbE LAN Port 4
USB 3.2 Gen 1 Port 2
Expansion Port 2
Expansion Port Type Infiniband
PCIe > PCIe Expansion 2 × Gen3 x8 slots (x8 link)
Appearance > Form Factor (RU) 2U
Size (Height × Width × Depth) 88 mm × 482 mm × 724 mm
Weight 14.5 kg
Rack Installation Support* 4-post 19" rack (Synology Rail Kit - RKS-02)
Notes #2 The rail kit is sold separately
Others > System Fan 80 mm × 80 mm × 4 pcs
Fan Speed Mode Full-Speed ModeCool ModeQuiet Mode
Noise Level 50.2 dB(A)
Power Supply Unit / Adapter 500 watts
AC Input Power Voltage 100V to 240V AC
Power Frequency 50/60 Hz, Single Phase
Power Consumption 142.76 watts (Access)55.05 watts (HDD Hibernation)
British Thermal Unit 487.12 BTU/hr (Access)187.84 BTU/hr (HDD Hibernation)
Notes #3 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 > Operating Temperature 5°C to 35°C (40°F to 95°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 FCCCEBSMIVCCIRCMEACCCCKCBIS
Warranty 5 Years
Notes #4 The warranty period starts from the purchase date as stated on your purchase receipt. (Learn more)
Environment RoHS Compliant
Packaging Content Main Unit × 1Accessory Pack × 1AC Power Cord × 1Quick Installation Guide × 1
Optional Accessories DDR4 ECC UDIMM: D4EC-2666-8G/D4EC-2666-16GExpansion Units: RX1217/RX1217RPEnterprise Series 3.5" SATA HDD: HAT5300 SeriesEnterprise Series 2.5" SATA SSD: SAT5200 SeriesM.2 SSD & 10GbE Combo Adapter Card: E10M20-T1M.2 SSD Adapter Card: M2D20/M2D1825GbE Network Interface Card: E25G30-F210GbE Network Interface Card: E10G30-F2/E10G30-T2/E10G18-T1Rail Kit Sliding: RKS-02
Notes #5 All memory modules will operate at the maximum frequency specified by the CPU manufacturer.
Storage Management > Maximum Single Volume Size 1 PB (64 GB memory required, for RAID 6 groups only)200 TB (32 GB memory required)108 TB
Maximum Internal Volume Number 128
Supported RAID Type RAID F1BasicJBODRAID 0RAID 1RAID 5RAID 6RAID 10
RAID Migration Basic to RAID 1Basic to RAID 5RAID 1 to RAID 5RAID 5 to RAID 6
Volume Expansion with Larger HDDs RAID F1RAID 1RAID 5RAID 6RAID 10
Volume Expansion by Adding a HDD RAID F1JBODRAID 5RAID 6
Global Hot Spare Supported RAID Type RAID F1RAID 1RAID 5RAID 6RAID 10
Notes #6 Volumes over 108 TB require 32 GB of memory or more.Certain conditions are required to support a 1 PB volume. Please refer to this article for more information.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.
File System > Internal Drives Btrfsext4
External Drives Btrfsext4ext3FAT32NTFSHFS+exFAT
File Services > File Protocol SMBAFPNFSFTPWebDAVRsync
Maximum Number of SMB Connections (FSCT-Based) 500
Notes #7 Connection value of this model is tested with Synology SATA SSD fully populated and up to four 10GbE network portsModels 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 > Maximum Local User Accounts 2,048
Maximum Local Groups 512
Maximum Shared Folder 512
Maximum Shared Folder Sync Tasks 12
Hybrid Share > Maximum Hybrid Share Folders 15
Hyper Backup Folder and Package Backup
Notes #8 Full-system backup requires DSM 7.2 or later.
High Availability Synology High Availability
Log Center > Syslog Events per Second 3,000
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 2025, Windows Server 2019, Windows Server 2016, Windows Server 2012 R2, Windows Server 2012
Citrix XenServer XenServer 7
OpenStack Cinder
General Specifications > Supported Protocols SMB1 (CIFS), SMB2, SMB3, NFSv3, NFSv4, NFSv4.1, NFS Kerberized sessions, iSCSI, Fibre Channel, HTTP, HTTPs, FTP, SNMP, LDAP, CalDAV
Supported Browsers ChromeFirefoxEdgeSafari
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 #9 For an updated list of supported browser versions, check the DSM Technical Specifications.
Synology AI Console Third-Party AI Model Integration
Maximum De-Identification Rate 500 words per second
Notes #10 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 > Maximum Number of Users 500
Notes #11 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
SAN Manager > Maximum iSCSI Target Number 64
Maximum LUN 128
Synology MailPlus / MailPlus Server > Free Email Accounts 5 (Additional accounts require purchase of licenses)
Maximum Number of Users 1,100
Notes #12 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 moreModels 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
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 > Default Licenses 2 (Additional cameras require purchase of licenses)
Maximum IP Cameras and Total FPS (H.264) 1080p: 75 channels, 2100 FPS3M: 75 channels, 1500 FPS5M: 75 channels, 900 FPS4K: 55 channels, 550 FPS
Maximum IP Cameras and Total FPS (H.265) 1080p: 75 channels, 2250 FPS3M: 75 channels, 2250 FPS5M: 75 channels, 1500 FPS4K: 75 channels, 900 FPS
Notes #13 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.The values above are based on testing with RTSP streaming. If SRTP is enabled for all cameras, overall performance will decrease to 70% of the stated figures.
Synology Drive > Maximum Number of Users 900
Maximum Number of Hosted Files 15,000,000 (applies to files indexed or hosted by Synology Drive. For file access through other standard protocols, refer to the File Services section above)
Notes #14 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 moreModels 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 900
Notes #15 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 moreModels 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)
Recommended Virtual DSM Number (Licenses required) 8 (including 1 Free License)
Notes #16 The specifications vary depending on system configuration and memory size.
VPN Server > Maximum Connections 12
