Synology NAS RS4021xs+ Manual

Synology NAS RS4021xs+
Hardware Installation Guide

Table of Contents
Chapter 1: Before You Start
Package Contents 3
Synology RS4021xs+ at a Glance 4
System Modes and LED Indicators 6
Other LED Indicators 8
Hardware Specication 9
Spare Parts 10
Optional Accessories 10
Safety Instructions 11
Chapter 2: Hardware Setup
Tools and Parts for Drive Installation 12
Install Drives 12
Install Memory Modules 14
Install PCle Add-in Cards 17
Install and Remove Rail Kits 18
Expansion Unit Deployment and Topology 20
Start up Your Synology NAS 21
Chapter 3: System Maintenance
Replace System Fan 22
Replace Power Supply Unit (PSU) 23
Chapter 4: Install DSM on Synology NAS
Install DSM with Web Assistant 24
Learn More 24
Synology_HIG_RS4021xs+_20200723
2

Synology NAS RS4021xs+ is an enterprise server consisting of both system hardware and the software operating
system, DiskStation Manager (DSM). This manual will guide you through all conguration aspects of your
RS4021xs+, including the hardware components, setup procedures, and system maintenance.
Note: All images below are for illustrative purposes only, and may di󰀨er from the actual product.
Package Contents
Main unit x 1 AC power cord x 2
Screws for 2.5" drives x 68
Screws for 3.5" drives x 68
Before You Start 1
Chapter
3

4Chapter 1: Before You Start
Synology RS4021xs+ at a Glance
6
15 2 3 4
77
810
15 16 1714
12
13
911
No. Article Name Location Description
1 POWER Button and
Indicator
Front
1. Press to power on your Synology NAS.
2. To power o󰀨 your Synology NAS, press and hold until you
hear a beep sound and the Power LED starts blinking.
2 STATUS Indicator Displays the status of the system. For more information, see
"System Modes and LED Indicators".
3 ALERT Indicator Displays warnings regarding fan or temperature. For more
information, see "Other LED Indicators".
4 Beep O󰀨 Button Press to deactivate the beep that sounds when a malfunction
occurs.
5 DRIVE Status
Indicator
Displays the status of drives. For more information, see "Other
LED Indicators".
6 Drive Tray Install drives (hard disk drives or solid state drives) here.
7 Rail Kit Release Tab Push in and hold to release your Synology NAS from the rail kit
lock.1
1For more information about the rail kit installation, please refer to the Quick Installation Guide that comes with the rail kit.

5Chapter 1: Before You Start
No. Article Name Location Description
8 PSU Fan
Back
Disposes of excess heat and cools the PSU.
9 Power Port Connect power cord here.
10 PSU Indicator Displays the status of the power supply unit (PSU). For more
information, see "Other LED Indicators".
11 Console Port This port is used for manufacturing only.
12 PCI Express
Expansion Slot Supports the addition of PCIe network interface cards.
13 1GbE RJ-45 Port Connect RJ-45 network cable here.
14 10GbE RJ-45 Port Connect RJ-45 network cable here.
15 USB 3.0 Port Connect external drives or other USB devices to the Synology
NAS here.
16 Expansion Port Connect to Synology Expansion Unit2here.
17 RESET Button
1. Press and hold until you hear a beep sound to restore the IP
address, DNS server, and password for the admin account to
default.
2. Press and hold until you hear a beep, then press and hold
again until you hear three beeps to return the Synology NAS
to “Not Installed” status so that DiskStation Manager (DSM)
can be reinstalled.
2For more information about Synology Expansion Unit supported by your Synology NAS, please visit www.synology.com.

6Chapter 1: Before You Start
6
System Modes and LED Indicators
System Modes and Denitions
There are 7 system modes in Synology NAS. The System modes and their denitions are as below:
System mode Denition
Powering on Synology NAS is powering on and performing hardware initialization, such as
hardware reset or BIOS initialization.
Shutting down Synology NAS is shutting down as a result of pressing the power button or operation
in DSM.
DSM not ready
DSM is not ready for use. This could either be:
• Synology NAS is powered on, but DSM is not properly installed.
• Synology NAS is currently powering on and initializing services necessary for
DSM to fully function.
• The attached UPS device has insu󰀩cient power; DSM stops all services to
prevent data loss (enters safe mode).
DSM is ready for use DSM is fully functioning and users can sign in.
Hibernation Synology NAS has been idle for a while and is now in Hibernation mode.
Application
Certain packages/services (e.g., USB Copy and Find me service) while in operation
will control the actions of the LED. After the operation is complete, the LED indicator
will return to its normal state.
Powered o󰀨 Synology NAS is powered o󰀨.
Identify System Modes
You can identify the system mode through the POWER and STATUS LED indicators. Please refer to below table
for more details.
System mode
LED Indicator
POWER STATUS
Blue Green Orange
Powering on Blinking O󰀨 O󰀨
Shutting down Blinking Static O󰀨
DSM not ready Static Blinking O󰀨
DSM is ready for use Static Static O󰀨
Hibernation Static O󰀨 O󰀨
Application Static Switching
Powered o󰀨 O󰀨 O󰀨 O󰀨

7Chapter 1: Before You Start
Transitions between System Modes
To better understand the transition between system modes, please refer to below examples:
• Powered on with no DSM installed:
Powered o󰀨 > Powering on > DSM not ready
• Powered on with DSM installed:
Powered o󰀨 > Powering on > DSM not ready > DSM is ready for use
• Enter hibernation then wake up from hibernation:
DSM is ready for use > Hibernation > DSM is ready for use
• Shutdown Synology NAS:
DSM is ready for use > Shutting down > Powered o󰀨
• Power failure with UPS attached:
DSM is ready for use > DSM not ready (due to power failure, DSM enters safe mode) > Shutting down >
Powered o󰀨 > Powering on (power has recovered, DSM will reboot)> DSM not ready > DSM is ready for use

8Chapter 1: Before You Start
Other LED Indicators
LED Indicator Color Status Description
DRIVE status
Green
Static Drive ready and idle
Blinking Accessing drive
Red Static Drive error/Port disabled1
O󰀨 No internal Drive
ALERT
Orange Blinking System error2
O󰀨 System normal
Rear PSU status
Green Static Power supply unit normal
Red Static Power supply unit fail/No power supply
O󰀨 Power supply unit o󰀨
Rear 1GbE LAN
(on left side of jack)
Green
Static Network connected
Blinking Network active
O󰀨 No network
Rear 1GbE LAN
(on right side of jack)
Green
Static
1 Gbps connected
Orange 100 Mbps connected
O󰀨 10 Mbps connected/No network
Rear 10GbE LAN
(on left side of jack)
Green
Static Network connected
Blinking Network active
O󰀨 No network
Rear 10GbE LAN
(on right side of jack)
Green
Static
10 Gbps connected
Orange 1 Gbps connected
O󰀨 100 Mbps connected/No network
Note:
1 Please try to restart your Synology NAS or re-insert the drives, then run the HDD/SSD manufacturer's
diagnostic tool to check the health status of the drives. If you can sign in to DSM, please run the built-in
S.M.A.R.T. test to scan the drives. If the problem remains unresolved, please contact Synology Technical
Support for help.
2 If the ALERT LED continuously blinks orange, this indicates there are system errors such as fan failure,
system overheating, or volume degrade. Please sign in to DSM for detailed information.

9Chapter 1: Before You Start
Hardware Specication
Item RS4021xs+
Compatible Drive Type 3.5"/2.5" SATA x 16
Maximum Drive Bays with
Expansion Unit 40 (RX1217/RX1217RP x 2)
External Port
• USB 3.0 x 2
• Inniband x 2
LAN Port
• 1GbE RJ-45 x 4
• 10GbE RJ-45 x 2
PCIe Slot Gen3 x8 slots (x8 link) x 2
Size (H x W x D) (mm)
• 132.3 x 430.5 x 624.5
• 132.3 x 482 x 656.5 (with server ears)
Weight (kg) 17.4
Supported Client
• Windows 7 onward
• macOS 10.12 onwards
File System
• Internal: Btrfs, ext4
• External: Btrfs, ext4, ext3, FAT32, NTFS, HFS+, exFAT1
Supported RAID Type
• Basic • JBOD • RAID 0 • RAID 1
• RAID 5 • RAID 6 • RAID 10 • Synology RAID F1
Agency Certication • FCC Class A • CE Class A • BSMI Class A
• EAC • VCCI • CCC • RCM • KC • UL • RoHS Compliant
HDD Hibernation Yes
Scheduled Power On/O󰀨 Yes
Wake on LAN Yes
Language Localization
Environment Requirement
• Line voltage: 100 V to 240 V AC
• Frequency: 50/60 Hz
• Operating Temperature: 32 to 95˚F (0 to 35˚C)
• Storage Temperature: -5 to 140˚F (-20 to 60˚C)
• Relative Humidity: 5% to 95% RH
Note: Model specications are subject to change without notice. Please refer to www.synology.com for the latest information.
9
1Support for exFAT can be enabled by purchasing and downloading exFAT Access in Package Center.

10 Chapter 1: Before You Start
Spare Parts
Visit www.synology.com/products/spare_parts if you need to replace system fans, disk trays, or power supply
units.
Model Name Picture Description
Cable MiniSAS_INT_3 Internal MiniSAS Cable
Disk Tray (Type R7) 3.5"/2.5" Drive Tray
FAN 80*80*32_7 System Fan 80*80*32 mm
PSU 800W-RP Module_1 Redundant PSU Module 800W
PSU 800W-RP SET_2 Redundant Power Set 800W
Optional Accessories
With Synology accessories, you can customize your expansion unit to t di󰀨erent business environments without
worrying about compatibility and stability. Visit www.synology.com/compatibility for more information.

11 Chapter 1: Before You Start
Safety Instructions
Keep away from direct sunlight and away from chemicals. Make sure the environment
does not experience abrupt changes in temperature or humidity.
Place the product right side up at all times.
Do not place near any liquids.
Before cleaning, unplug the power cord. Wipe with damp paper towels. Do not use
chemical or aerosol cleaners.
To prevent the unit from falling over, do not place on carts or any unstable surfaces.
The power cord must plug in to the correct supply voltage. Make sure that the supplied
AC voltage is correct and stable.
To remove all electrical current from the device, ensure that all power cords are
disconnected from the power source.
Risk of explosion if battery is replaced with an incorrect type. Dispose of used batteries
appropriately.

Tools and Parts for Drive Installation
Please prepare below tools and parts before setting up your Synology NAS:
• A screwdriver
• At least one 3.5" or 2.5" SATA drive (please visit www.synology.com for compatible drive models)
Warning: If you install a drive that contains data, the system will format the drive and erase all existing data.
Please back up any important data before installation.
• Rail mounting kit (please see the Optional Accessories section to nd out the suitable rail kit for cabinet
installation)
Warning: We suggest mounting your Synology NAS on a cabinet before installing any drives since the heavy
weight will increase the installation di󰀩culty.
Install Drives
Please follow the steps below for drive installation:
1 Open the drive tray.
a
b
RS4021xs+
a Press the small button located on the left side of the drive tray handle. The drive tray handle pops out.
b Pull the drive tray out by its handle as shown above.
2 Install drives:
• For 3.5” drives: Place the drive in the drive tray. Turn the tray upside down and tighten screws into the four
spots indicated below to secure the drive in place.
Hardware Setup
12
2
Chapter

13 Chapter 2: Hardware Setup
• For 2.5” drives: Place the drive in the drive tray. Turn the tray upside down and tighten screws into the four
spots indicated below to secure the drive in place.
3 Insert the loaded drive tray into the empty drive bay.
RS4021xs+
Note: Make sure that the drive tray is completely inserted. Otherwise, the drive might not function properly.
4 Push the handle inward to secure the drive tray.
5 Push the switch to the left on the drive tray handle to lock the drive tray.
RS4021xs+
6 Repeat the steps above to install the other drives you have prepared.
7 Drives are numbered as shown below.
1 2 43
5678
9 10 1211
13 15 16
14
Note: If you plan to create a RAID volume, we recommend installing drives of identical size to make the best
use of drive capacity.

14 Chapter 2: Hardware Setup
Install Memory Modules
Genuine Synology memory modules must be installed to ensure system compatibility and reliability. Failure
to follow the congurations below for the suggested installation sequence of di󰀨erent memory capacities may
prevent the system from booting successfully, and could impair system performance and stability.
A0 A1 B0 B1 Total Memory
16GB - - - 16GB
16GB - 16GB - 32GB
16GB 16GB 16GB - 48GB
16GB 16GB 16GB 16GB 64GB
Note: It is required to use identical memory modules of the same capacity and frequency.
Follow the steps below to install, check, or remove a memory module on your RS4021xs+.
To install the RAM module
1 Shut down your RS4021xs+. Disconnect all cables connected to your RS4021xs+ to prevent any possible
damage.
2 Remove the screw on the back of you RS4021xs+. Slide open the rear top cover, then lift it up and put it aside.
Note: When you remove the rear top cover, sensitive internal components are exposed. Avoid touching
anything other than the memory assembly when removing or adding memory.

15 Chapter 2: Hardware Setup
3 Insert the new memory module in the slot:
a Push the retaining clips on the slot out to the sides.
b Align the notch on the gold edge of the module with the notch in the memory slot.
c Apply rm and even pressure to push down the memory module. The retaining clips will snap into position
when the module is inserted correctly.
a
b
c
Note: Hold the memory module by its edges and avoid touching the gold connectors.
4 Place the rear top cover back and slide it into secure position:
a Align the hexagons at the side of the rear top cover with the slots on the chassis' edge, place it back and
push it to slide it back into position.
b Put back and fasten the screw you removed in step 2.
To conrm that your RS4021xs+ recognizes the new memory capacity
1 Install DiskStation Manager (DSM). Please see "Install DSM on Synology NAS" for more information.
2 Sign in to DSM as admin or a user belonging to the administrators group.
3 Go to Control Panel > Info Center and check Total Physical Memory.
If your Synology NAS does not recognize the memory or does not start up successfully, please make sure that
the memory module is installed correctly.

16 Chapter 2: Hardware Setup
To remove the RAM Module
1 Follow step 1 and 2 of the "To install the RAM module" section to shut down your RS4021xs+, disconnect the
cables, and then remove the rear top cover as described above.
2 Cut the cable tie before removing the memory module. (The pre-installed memory module is cable-tied to
prevent it from loosening during delivery.)
Note: Avoid touching any components on the motherboard when cutting the cable tie.
3 Push the retaining clips on the slot out to the sides. The memory module will pop out of the slot.
4 Follow step 4 of the "To install the RAM module"section to fasted the top cover back in place.

17 Chapter 2: Hardware Setup
Install PCle Add-in Cards
RS4021xs+ provides two PCIe slots for optional add-in card expansion, allowing network interface cards to be
installed.
To install network interface cards
1 Shut down your RS4021xs+. Disconnect all cables connected to your RS4021xs+ to prevent any possible
damages.
2 Open your RS4021xs+ by following step 2 of the "To install the RAM module" section.
3 Install the network interface card:
a Remove the screw that secures the expansion slot’s cover.
b Lift the expansion slot’s cover.
ab
c Align the card’s connector with the expansion slot, and insert the card into the slot.
Note: Conrm that the connector is fully inserted. Otherwise, the network interface card might not be able to
function properly.
d Put back and fasten the screw that you removed in step 3-a to secure the newly inserted card in place.
d
c
4 Repeat step 3 to install another network interface card for your RS4021xs+.
5 Replace the rear top cover by following step 4 of the "To install the RAM module" section.

18 Chapter 2: Hardware Setup
Install and Remove Rail Kits
Here we use RKS1317 as an example to illustrate how to install or remove the rail kits. For more information
about the rail kit installation, please refer to the Quick Installation Guide that comes with the rail kit.
To install the rail kit
1 To install the rail kit to the rack:
e Attach the rear end of the rail kit assembly to the rack.
f Slide the front latch outwards and insert the brackets into the rack holes.
2 Extend the inner rail from the assembly and pull it out.
3 Align the xing holes of the inner rail to the attachment points on the side of the chassis. Slide the inner rail
away from the front panel to attach it to the chassis.

19 Chapter 2: Hardware Setup
4 With the help of another person, carefully align the inner rail to the outer rail assembly.
5 Pull and hold the blue front latch of the inner rail to unlock the inner rail. Push the chassis into the rack. Use the
cage nuts and screws enclosed with the rail kit package to secure the chassis to the rack if necessary.
To remove the rail kit
1 To remove the chassis from the rack, press the rail kit release tabs on the ear holders inward and pull the
chassis out of the rack.
2 With the help of another person, carefully remove the chassis from the rack. Then, slide the inner rail attached
to the chassis toward the front panel of the chassis to detach it.

20 Chapter 2: Hardware Setup
Expansion Unit Deployment and Topology
RS4021xs+ supports RX1217/RX1217RP (12-bay) expansion units, providing seamless storage expansion
whenever needed. This section will guide you through how to connect the expansion units to your Synology NAS.
To connect RX1217/RX1217RP with RS4021xs+
1 Here we use RX1217RP as an example to illustrate how to connect to the expansion units. Connect one end
of the expansion cable to the expansion port of the RS4021xs+ and the other to the expansion port of the
expansion units.
RX1217RP
RX1217RP
RS4021xs+
2 Connect the power cords:
a For RX1217RP, connect one end of both power cords to a power port on the RX1217RP, and the other to
a power outlet.
Note: Your RX1217RP comes equipped with a redundant power supply system, allowing two power cords to
be connected. The system may be powered on with only one power cord, but we recommend using two power
cords to avoid unexpected power failures.
b For RX1217, connect one end of power cord to a power port on the RX1217, and the other to a power
outlet. Press the PSU switch located on the back panel to switch the PSU on.