Synology RackStation RS4021XS+ NAS/storage server Rack (3U) Ethernet LAN Black D-1541

Securing your business assets
The 16-bay RS4021xs+ provides solid data security and lightening-fast performance with over 234K 4K random read IOPS and 6,258 MB/s sequential read throughput1. Together with its 8-core processor, ECC memory, advanced snapshot technology, and built-in 10GbE connectivity, the RS4021xs+ can support large multi-user environments while handling data-intensive workloads.

Engineered for service continuity
The RS4021xs+ ensures mission-critical data is always available, enabling businesses to deliver the best results, even in the face of disaster.

Redundant power
Dual PSUs provide protection against a PSU failure or accidental cord removal while hot-swappable fans can be replaced without powering down the system.

Maximize service availability
Synology High Availability (SHA) pairs two identical units together creating an active-passive cluster with minute-level failover.

Next-generation file system
Btrfs prevents data corruption and reduces maintenance overheads with advanced storage technologies and optimized snapshots

Customize to your business
The RS4021xs+ includes two PCIe slots for performance, networking, and storage upgrades enabling it to adapt to any business environment2.

Double bandwidth
Upgrade network bandwidth in minutes by 2x or more with Synology’s range of 10GbE NICs.

SSD cache3
Boost read/write IOPS by up to 16 times by enabling SSD cache with our Synology M.2 NVMe adapter cards and SNV3500 SSDs, or by installing one or more 2.5” SAT5200 SSDs.

Storage expansion
Quickly and easily scale up to 40 drives with two RX1217(RP) expansion units.

Hyper Backup
A comprehensive backup and recovery solution for securing data stored on Synology servers. Backup data locally, to another Synology device, rsync server, or cloud-based storage such as Google Drive, Dropbox, S3-compatible destinations, and Synology C2. Deduplication4, integrity checks, and incremental transfer technology reduce bandwidth and storage used.

Snapshot Replication
Easily schedule flexible point-in-time backups of shared folders and iSCSI LUNs with an RPO as low as 5 minutes and recovery in seconds. Set up replication and failover to other Synology storage systems for fast RTOs and minimal service disruption.

Storage for virtualization
Synology iSCSI storage supports mainstream virtualization solutions with an easy management interface to enhance usability. VMware vSphere 6.5 and VAAI integration helps offload storage operations. Windows Offloaded Data Transfer (ODX) speeds up data transfer. OpenStack Cinder support turns your Synology NAS into a block-based storage component. Additionally, Synology Storage Console enables even more simplified storage provisioning and management options in VMware and Windows environments

All-in-one surveillance solution
Synology Surveillance Station transforms the RS4021xs+ into a feature-packed Network Video Recorder solution. Support for up to 90 IP cameras5 and video analytics such as motion detection, no idle zone, foreign object detection, and anomaly detection cater to the most common surveillance scenarios.

Secure and private
AES-256 encryption keeps locally-stored footage secure.

Access from anywhere, anytime
Access recordings and live streams whenever you want using a web browser, desktop client, or the DS cam mobile app.

Real-time alerts
Email, SMS, or push notifications alert you when incidents occur or predefined conditions are met.

Storage drive interface	Serial ATA II, Serial ATA III
Storage drive sizes supported	2.5,3.5"
RAID support	Yes
RAID levels	5, 6
Storage drives installed	No
Number of storage drives supported	16
Installed storage drive type	No
Supported storage drive types	HDD & SSD
Processor manufacturer	Intel
Processor family	Intel® Xeon®
Processor model	D-1541
Processor frequency	2.1 GHz
Processor boost frequency	2.7 GHz
Processor cores	8
CPU configuration (max)	1
Number of processors supported	1
Conflict-Free processor	Yes
Internal memory	16 GB
Internal memory type	DDR4
Maximum RAM supported	64 GB
Memory slots	4
Memory form factor	UDIMM
ECC	Yes
Ethernet LAN	Yes
Ethernet LAN data rate supported (max)	10000 Mbit/s
Wake-on-LAN ready	Yes
USB port	Yes
USB 3.2 Gen 1 (3.1 Gen 1) Type-A ports quantity	2
Ethernet LAN (RJ-45) ports	6
PCI Express x8 (Gen 3.x) slots	2
Chassis type	Rack (3U)
Cooling type	Active
Product colour	Black
Number of fans	3 fan(s)
Fan diameter	8 cm
Built-in display	No
Built-in speaker(s)	No
Type	Storage server
Device class	Small & Medium Business
Backup function	Yes
Noise level	44.7 dB
On/off switch	Yes
Power supply unit (PSU) capacity	800 W
Redundant power supply (RPS) support	Yes
Power consumption (typical)	145.79 W
Power consumption (HDD standby)	62.68 W
AC input voltage	100 - 240 V
AC input frequency	50 - 60 Hz
Width	482 mm
Depth	656.5 mm
Height	132.3 mm
Weight	17.4 kg
Power cables quantity	2
Embedded options available	No
Enhanced Intel SpeedStep Technology	Yes
Execute Disable Bit	Yes
Idle States	Yes
Intel 64	Yes
Intel Enhanced Halt State	Yes
Intel Secure Key Technology version	1.00
Intel Trusted Execution Technology	Yes
Intel TSX-NI	Yes
Intel TSX-NI version	1.00
Intel Virtualization Technology (VT-x)	Yes
Intel Virtualization Technology for Directed I/O (VT-d)	Yes
Intel VT-x with Extended Page Tables (EPT)	Yes
Operating temperature (T-T)	0 - 35 °C
Operating relative humidity (H-H)	5 - 95%
Storage temperature (T-T)	-20 - 60 °C
Harmonized System (HS) code	84714100
Certification	FCC CE BSMI VCCI RCM EAC CCC KC UL