RackStation RS4021xs+

Enterprise NAS with built-in service continuity engineered for data-intensive applications.

Rackmount Nas / 16-Bays

CPU	CPU Model	Intel Xeon D-1541
	CPU Quantity	1
	CPU Architecture	64-bit
	CPU Frequency	8-core 2.1 (base) / 2.7 (turbo) GHz
	Hardware Encryption Engine (AES-NI)
Memory	System Memory	16 GB DDR4 ECC UDIMM
	Memory Module Pre-installed	16 GB (16 GB x 1)
	Total Memory Slots	4
	Maximum Memory Capacity	64 GB (16 GB x 4)
	Notes	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 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.
Storage	Drive Bays	16
	Maximum Drive Bays with Expansion Unit	40 (RX1217/RX1217RP x 2)
	Compatible Drive Type*	3.5″ SATA HDD 2.5″ SATA SSD
	Maximum Single Volume Size*	200 TB (32 GB memory required) 108 TB
	Hot Swappable Drive
	Notes	“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. Each internal volume (may consist of multiple drives) is expandable up to 108 TB (with memory less than 32 GB) or 200 TB (with memory equal to or greater than 32 GB).
External Ports	RJ-45 1GbE LAN Port	4 (with Link Aggregation / Failover support)
	RJ-45 10GbE LAN Port	2 (with Link Aggregation / Failover support)
	USB 3.2 Gen 1 Port*	2
	Expansion 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 Expansion	2 x Gen3 x8 slots (x8 link)
File System	Internal Drives	Btrfs EXT4
	External Drives	Btrfs EXT4 EXT3 FAT NTFS HFS+ exFAT*
	Notes	exFAT Access is purchased separately in Package Center.
Appearance	Form Factor (RU)	3U
	Size (Height x Width x Depth)	132.3 mm x 482 mm x 656.5 mm
	Weight	17.4 kg
	Rack Installation Support*	4-post 19″ rack (Synology Rail Kit RKS1317)
	Notes	The rail kit is sold separately
Others	System Fan	80 mm x 80 mm x 3 pcs
	Fan Speed Mode	Full-Speed Mode Cool Mode Quiet Mode
	Easy Replacement System Fan
	Power Recovery
	Noise Level*	44.7 dB(A)
	Scheduled Power On / Off
	Wake on LAN / WAN
	Power Supply Unit / Adapter	800 W
	Redundant Power Supply
	AC Input Power Voltage	100 V to 240 V AC
	Power Frequency	50/60 Hz, Single Phase
	Power Consumption*	145.79 W (Access) 62.68 W (HDD Hibernation)
	British Thermal Unit	497.14 BTU/hr (Access) 213.74 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	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
Certification	FCC CE BSMI EAC KC VCCI RCM
Warranty	5 Years
	Notes	The warranty period starts from the purchase date as stated on your purchase receipt.
Environment	RoHS Compliant
Packaging Content	Main Unit X 1 Accessory Pack X 1 AC Power Cord X 2 Quick Installation Guide X 1
Optional Accessories	DDR4 ECC RDIMM: D4RD-2666-16G/D4RD-2666-32G Expansion Units: FX2421/RX1217sas 2.5″ SATA SSD: SAT5200 25GbE Network Interface Card: E25G21-F2 10GbE Network Interface Card: E10G21-F2/E10G18-T2/E10G18-T1 Rail Kit Sliding: RKS1317 VisualStation: VS960HD/VS360HD Surveillance Device License Pack
	Notes	It is required to use D4RD-2666-16G with identical memory modules of the same capacity and frequency.

Storage Management	Maximum Internal Volume Number	256
	SSD Read / Write Cache
	SSD TRIM
	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 RAID 5 to RAID 6
	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
File Services	File Protocol	SMB/AFP/NFS/FTP/WebDAV
	Maximum Concurrent SMB/AFP/FTP Connections	4,000
	Maximum Concurrent SMB/AFP/FTP Connections (with RAM expansion)	10,000
	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. 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.
Account & Shared Folder	Maximum Local User Accounts	16,000
	Maximum Local Groups	512
	Maximum Shared Folder	512
	Maximum Shared Folder Sync Tasks	32
High Availability	Synology High Availability
Log Center	Syslog Events per Second	3,000
Virtualization	VMware vSphere with VAAI
	Windows Server 2016
	Windows Server 2019
	Citrix Ready
	OpenStack
General Specifications	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 Internet Explorer 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
Antivirus by McAfee (Trial)
Central Management System
Synology Chat	Maximum Users	6,000
	Notes	The number of concurrent HTTP connections for Synology Chat was configured to the maximum. For tested models with expandable memory, the maximum amount of RAM was installed.
Document Viewer
exFAT Access (Optional)
iSCSI Manager	Maximum iSCSI Target Number	256
	Maximum iSCSI LUN	512
	iSCSI LUN Clone/Snapshot, Windows ODX
Synology MailPlus / MailPlus Server	Free Email Accounts	5 (Licenses required for additional accounts)
	Maximum Number of Concurrent Users	1,100
	Maximum Server Performance	4,312,000 emails per day, approx. 131GB
	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).
Snapshot Replication	Maximum Snapshots per Shared Folder	1,024
	Maximum of System Snapshots	65,536
Surveillance Station	Maximum IP cam (Licenses required)	90 (including 2 Free License)
	Total FPS (H.264)	2700 FPS @ 720p (1280×720) 2250 FPS @ 1080p (1920×1080) 1500 FPS @ 3M (2048×1536) 900 FPS @ 5M (2591×1944) 550 FPS @ 4K (3840×2160)
	Total FPS (H.265)	2700 FPS @ 720p (1280×720) 2700 FPS @ 1080p (1920×1080) 2250 FPS @ 3M (2048×1536) 1500 FPS @ 5M (2591×1944) 1080 FPS @ 4K (3840×2160)
	Notes	Surveillance Station throughput is tested with Axis network camera, using continuous recording with live view from Surveillance Station and motion detection by camera. Live view and recording are sharing the same stream from the camera. The maximum channel number also includes devices installed on Virtual DSM. Total FPS may be affected by other services running at the same time (e.g., archive tasks performed by Archive Vault).
Synology Drive	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)
	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)
	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.
Synology Office	Maximum Users	3,000
	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
Virtual Machine Manager	Recommended Virtual Machine Instances	16
	Recommended Virtual DSM Number	16 (including 1 Free License)
	Notes	The specifications vary depending on system configuration and memory size.
VPN Server	Maximum Connections	40
Media Server	DLNA Compliance
Moments	Facial Recognition
	Subject Recognition
	Auto Color & Rotate
	Moments Select
PetaSpace
Video Station