Dell PowerEdge XR7620 Manual

Dell PowerEdge XR7620
Installation and Service Manual
Regulatory Model: E89S
Regulatory Type: E89S001
May 2023
Rev. A00

Notes, cautions, and warnings
NOTE: A NOTE indicates important information that helps you make better use of your product.
CAUTION: A CAUTION indicates either potential damage to hardware or loss of data and tells you how to avoid
the problem.
WARNING: A WARNING indicates a potential for property damage, personal injury, or death.
© 2023 Dell Inc. or its subsidiaries. All rights reserved. Dell Technologies, Dell, and other trademarks are trademarks of Dell Inc. or its
subsidiaries. Other trademarks may be trademarks of their respective owners.

Chapter 1: About this document.................................................................................................... 8
Chapter 2: System overview..........................................................................................................9
Front Accessed Configuration (Reverse Airflow) for XR7620............................................................................... 10
System configurations - front view for PowerEdge XR7620............................................................................10
System configurations - rear view for PowerEdge XR7620 ............................................................................ 12
System configurations - inside view for PowerEdge XR7620...........................................................................13
Rear Accessed Configuration (Normal Airflow) for XR7620...................................................................................14
System configurations - front view for PowerEdge XR7620............................................................................14
System configurations - rear view for PowerEdge XR7620..............................................................................15
System configurations - inside view for PowerEdge XR7620...........................................................................17
Bezel view............................................................................................................................................................................18
Bezel overview..............................................................................................................................................................19
Status LED control panel................................................................................................................................................. 21
Power button control panel............................................................................................................................................ 22
Locating the Express Service Code and Service Tag...............................................................................................22
System information labels............................................................................................................................................... 24
Rail sizing and rack compatibility matrix...................................................................................................................... 28
Chapter 3: Technical specifications............................................................................................. 29
Chassis dimensions ..........................................................................................................................................................30
System weight.................................................................................................................................................................... 31
Processor specifications...................................................................................................................................................31
PSU specifications.............................................................................................................................................................31
Supported operating systems........................................................................................................................................ 32
Cooling fan specifications............................................................................................................................................... 32
Expansion card riser specifications............................................................................................................................... 33
Memory specifications..................................................................................................................................................... 33
Storage controller specifications...................................................................................................................................34
Drives................................................................................................................................................................................... 34
GPU specifications............................................................................................................................................................34
System battery specifications........................................................................................................................................34
Ports and connectors specifications............................................................................................................................ 35
USB ports specifications........................................................................................................................................... 35
NIC port specifications.............................................................................................................................................. 35
Serial connector specifications................................................................................................................................ 35
VGA ports specifications........................................................................................................................................... 36
Video specifications..........................................................................................................................................................36
Environmental specifications..........................................................................................................................................36
Thermal restriction matrix.........................................................................................................................................39
Chapter 4: Initial system setup and configuration........................................................................43
Setting up the system......................................................................................................................................................43
iDRAC configuration......................................................................................................................................................... 43
Contents
Contents 3

Options to set up iDRAC IP address.......................................................................................................................43
Options to log in to iDRAC........................................................................................................................................ 44
Resources to install operating system......................................................................................................................... 45
Options to download drivers and firmware ..........................................................................................................45
Options to download and install OS drivers .........................................................................................................45
Downloading drivers and firmware..........................................................................................................................46
Chapter 5: Pre-operating system management applications........................................................ 47
System Setup..................................................................................................................................................................... 47
System BIOS.................................................................................................................................................................48
iDRAC Settings............................................................................................................................................................ 69
Device Settings............................................................................................................................................................70
Service Tag Settings...................................................................................................................................................70
Dell Lifecycle Controller...................................................................................................................................................70
Embedded system management..............................................................................................................................70
Boot Manager.....................................................................................................................................................................70
PXE boot............................................................................................................................................................................. 70
Chapter 6: Minimum to POST and system management configuration validation..........................71
Minimum configuration to POST ...................................................................................................................................71
Configuration validation....................................................................................................................................................71
Error messages.............................................................................................................................................................72
Chapter 7: Installing and removing system components ..............................................................73
Safety instructions............................................................................................................................................................ 73
Before working inside your system ..............................................................................................................................74
After working inside your system.................................................................................................................................. 74
Recommended tools......................................................................................................................................................... 74
Optional front bezel .........................................................................................................................................................75
Removing the front bezel..........................................................................................................................................75
Installing the front bezel............................................................................................................................................ 76
Bezel filter........................................................................................................................................................................... 77
Removing the bezel filter...........................................................................................................................................78
Installing the bezel filter ............................................................................................................................................79
System cover..................................................................................................................................................................... 80
Removing the system cover..................................................................................................................................... 80
Installing the system cover....................................................................................................................................... 82
Air shrouds.......................................................................................................................................................................... 84
Removing the 2U air shroud..................................................................................................................................... 84
Installing the 2U air shroud....................................................................................................................................... 84
Removing the 1U air shroud......................................................................................................................................85
Installing the 1U air shroud........................................................................................................................................ 86
Drives....................................................................................................................................................................................87
Removing a drive blank.............................................................................................................................................. 87
Installing a drive blank................................................................................................................................................ 88
Removing a drive carrier............................................................................................................................................89
Installing the drive carrier..........................................................................................................................................90
Removing the drive from the drive carrier............................................................................................................92
Installing the drive into the drive carrier................................................................................................................93
4Contents

Drive cage........................................................................................................................................................................... 95
Removing the drive cage...........................................................................................................................................95
Installing the drive cage.............................................................................................................................................96
PERC module..................................................................................................................................................................... 98
Removing the fPERC module ..................................................................................................................................98
Installing the fPERC module..................................................................................................................................... 98
Drive backplane................................................................................................................................................................. 99
Drive backplane............................................................................................................................................................99
Removing the drive backplane .............................................................................................................................. 100
Installing the drive backplane..................................................................................................................................102
Cable routing.....................................................................................................................................................................104
Expansion cards and expansion card risers...............................................................................................................122
Expansion card installation guidelines...................................................................................................................122
Removing the Expansion card riser 2....................................................................................................................127
Installing the Expansion card riser 2......................................................................................................................127
Removing the Expansion card riser 1.................................................................................................................... 128
Installing the Expansion card riser 1...................................................................................................................... 129
Removing the expansion card Expansion card riser 3...................................................................................... 130
Installing the expansion card riser 3.......................................................................................................................131
Removing expansion card or GPU from the Expansion card riser 2............................................................. 132
Installing an expansion card or GPU into the Expansion card riser 2............................................................134
Removing expansion card or GPU from the Expansion card riser 1.............................................................. 136
Installing an expansion card or GPU into the expansion card riser 1.............................................................139
Removing expansion card from the expansion card riser 3..............................................................................141
Installing an expansion card into the expansion card riser 3........................................................................... 142
Side wall brackets............................................................................................................................................................144
Removing the side wall bracket..............................................................................................................................144
Installing the side wall bracket................................................................................................................................145
Cooling fans...................................................................................................................................................................... 146
Removing a cooling fan............................................................................................................................................ 146
Installing a cooling fan...............................................................................................................................................147
Fan board...........................................................................................................................................................................148
Removing a fan board...............................................................................................................................................148
Installing a fan board.................................................................................................................................................149
M.2 BOSS card................................................................................................................................................................ 150
Removing BOSS riser............................................................................................................................................... 150
Installing BOSS riser.................................................................................................................................................. 151
Removing the M.2 BOSS card from the M.2 BOSS riser................................................................................ 152
Installing the M2 BOSS card into the M.2 BOSS riser..................................................................................... 153
Removing the M.2 SSD module..............................................................................................................................154
Installing the M.2 SSD module................................................................................................................................155
System memory............................................................................................................................................................... 156
System memory guidelines...................................................................................................................................... 156
General memory module installation guidelines.................................................................................................. 158
Removing a memory module...................................................................................................................................158
Installing a memory module..................................................................................................................................... 159
Processor and heat sink module.................................................................................................................................. 160
Removing the processor and heat sink module..................................................................................................160
Removing the processor.......................................................................................................................................... 162
Installing the processor............................................................................................................................................ 163
Contents 5

Installing the processor and heat sink module....................................................................................................166
System battery ................................................................................................................................................................168
Replacing the system battery.................................................................................................................................168
Optional internal USB card............................................................................................................................................ 170
Removing the internal USB card............................................................................................................................170
Installing the internal USB card............................................................................................................................... 171
Intrusion switch.................................................................................................................................................................171
Removing the intrusion switch module..................................................................................................................171
Installing the intrusion switch module................................................................................................................... 172
Optional serial COM port............................................................................................................................................... 173
Removing the serial COM port............................................................................................................................... 173
Installing the serial COM port................................................................................................................................. 174
Power supply unit............................................................................................................................................................ 175
Hot spare feature.......................................................................................................................................................175
Removing a power supply unit blank.....................................................................................................................176
Installing a power supply unit blank....................................................................................................................... 176
Removing a power supply unit................................................................................................................................ 177
Installing a power supply unit..................................................................................................................................178
Power interposer board..................................................................................................................................................179
Removing the power interposer board................................................................................................................. 179
Installing the power interposer board................................................................................................................... 180
Optional OCP card........................................................................................................................................................... 181
Removing the OCP card........................................................................................................................................... 181
Installing the OCP card.............................................................................................................................................183
System board....................................................................................................................................................................184
Removing the system board....................................................................................................................................184
Installing the system board......................................................................................................................................185
Trusted Platform Module...............................................................................................................................................188
Upgrading the Trusted Platform Module............................................................................................................. 188
Initializing TPM for users......................................................................................................................................... 189
Initializing the TPM 2.0 for users...........................................................................................................................189
Control panel.....................................................................................................................................................................189
Removing the Status LED control panel.............................................................................................................. 189
Installing the Status LED control panel................................................................................................................. 191
Removing the Power button control panel..........................................................................................................192
Installing the Power button control panel............................................................................................................193
Chapter 8: MIL kit......................................................................................................................196
Installing the MIL kit........................................................................................................................................................196
Chapter 9: Upgrade Kits.............................................................................................................198
Chapter 10: Jumpers and connectors......................................................................................... 199
System board jumpers and connectors......................................................................................................................199
System board jumper settings......................................................................................................................................201
Disabling a forgotten password....................................................................................................................................201
Chapter 11: System diagnostics and indicator codes.................................................................. 202
Bezel LED indicator........................................................................................................................................................ 202
6Contents

Status LED indicators.................................................................................................................................................... 202
System health and system ID indicator codes.........................................................................................................204
Power supply unit indicator codes..............................................................................................................................205
NIC indicator codes........................................................................................................................................................206
Drive indicator codes......................................................................................................................................................207
EDSFF E3 drive led codes.............................................................................................................................................207
iDRAC Direct LED indicator codes..............................................................................................................................208
Using system diagnostics..............................................................................................................................................208
Dell Embedded System Diagnostics..................................................................................................................... 209
Chapter 12: Getting help............................................................................................................ 210
Recycling or End-of-Life service information...........................................................................................................210
Contacting Dell Technologies....................................................................................................................................... 210
Accessing system information by using QRL............................................................................................................210
Quick Resource Locator for PowerEdge XR7620 system................................................................................211
Receiving automated support with Secure Connect Gateway (SCG)................................................................ 211
Chapter 13: Documentation resources........................................................................................ 213
Contents 7

About this document
This document provides an overview about the system, information about installing and replacing components, diagnostic tools,
and guidelines to be followed while installing certain components.
1
8 About this document

System overview
The Dell PowerEdge XR7620 is 2-socket, 2U server that supports:
●Rear Accessed Configuration (Normal Airflow) and Front Accessed Configuration (Reverse Airflow)
●Two 4th Generation Intel® Xeon® Scalable Processors with up to 32 cores per processor
●Up to 16 DDR5 DIMM slots
●Two redundant AC or DC power supply units
●Up to five PCIe slots (2 x16 Gen4/5, 2 x16 Gen4, 1 x16 LP Gen4) for networking, enabling flexible networking design
●Up to 4 x 2.5-inch SAS/SATA/NVMe Solid State Drives (SSDs), or 8 x E3.S NVMe drives
NOTE: Front-accessed configurations cannot be converted to Rear-accessed configurations, and vice versa.
NOTE: For more information about how to hot swap NVMe PCIe SSD U.2 device, see the Dell Express Flash NVMe
PCIe SSD User's Guide at https://www.dell.com/support > Browse all Products > Data Center Infrastructure > 
Storage Adapters & Controllers > Dell PowerEdge Express Flash NVMe PCIe SSD > Documentation > Manuals
and Documents.
NOTE: All instances of SAS, SATA drives are referred to as drives in this document, unless specified otherwise.
CAUTION: Do not install GPUs, network cards, or other PCIe devices on your system that are not validated
and tested by Dell. Damage caused by unauthorized and invalidated hardware installation will null and void the
system warranty.
Topics:
•Front Accessed Configuration (Reverse Airflow) for XR7620
•Rear Accessed Configuration (Normal Airflow) for XR7620
•Bezel view
•Status LED control panel
•Power button control panel
•Locating the Express Service Code and Service Tag
•System information labels
•Rail sizing and rack compatibility matrix
2
System overview 9

Front Accessed Configuration (Reverse Airflow) for
XR7620
System configurations - front view for PowerEdge XR7620
Figure 1. Front view of Front Accessed configuration with bezel
Figure 2. Front view of Front Accessed 4 x 2.5-inch drive configuration without bezel
Figure 3. Front view of Front Accessed E3.S drive configuration without bezel
10 System overview

Table 1. Features available on the front view of Front Accessed E3.S configuration
Item Ports, panels, or slots Icon Description
1 Status LED control panel N/A Contains the system health,
system ID, status LED.
●Status LED: Enables you
to identify any failed
hardware components.
There are five status LEDs
and an overall system
health LED (Chassis health
and system ID) bar. For
more information, see
the Status LED indicators
section.
2 PCIe expansion card riser 1
(slot 1)
N/A Enables you to connect PCI
Express expansion cards.
3 PCIe expansion card riser 1
(slot 2)
N/A Enables you to connect PCI
Express expansion cards.
4 PCIe expansion card riser 2
(slot 3)
N/A Enables you to connect PCI
Express expansion cards.
5 PCIe expansion card riser 2
(slot 4)
N/A Enables you to connect PCI
Express expansion cards.
6 Drive N/A Enables you to install up to 4
x 2.5-inch, or 8 x E3.S Solid-
State Drives (SSDs)
7 Power button control panel N/A Contains the power button,
USB port, iDRAC Direct micro
USB port, and the iDRAC
Direct status LED.
8 Power supply unit (PSU 2)
and (PSU 1)
Indicates the PSU2
(redundant PSU) and PSU1
(primary PSU)
9System identification button Press the system ID button:
●To locate a particular
system within a rack.
●To turn the system ID on
or off.
To reset iDRAC, press and
hold the button for 16
seconds.
NOTE:
●To reset iDRAC using
system ID, ensure that
the system ID button is
enabled in the iDRAC
setup.
●If the system stops
responding during
POST, press and hold
the system ID button
(for more than five
seconds) to enter the
BIOS progress mode.
10 VGA port Enables you to connect a
display device to the system.
System overview 11

Table 1. Features available on the front view of Front Accessed E3.S configuration(continued)
Item Ports, panels, or slots Icon Description
11 PCIe expansion card riser 3
(Low profile slot 5)
N/A Enables you to connect PCI
Express expansion cards.
12 OCP NIC card (optional) N/A The OCP NIC card supports
OCP 3.0. The NIC ports are
integrated on the OCP card
which is connected to the
system board.
13 USB 2.0 port This port is USB 2.0-
compliant.
14 USB 3.0 port This port is USB 3.0-
compliant.
15 iDRAC dedicated port It is an RJ-45 port.
Enables you to remotely
access iDRAC. For more
information, see the
Integrated Dell Remote
Access Controller User's
Guide at www.dell.com/
poweredgemanuals.
16 2 x LOM ports The LOM ports that are
integrated on the system
board provide network
connectivity. These LOM
ports can also be shared with
iDRAC when iDRAC network
settings is set to shared
mode.
System configurations - rear view for PowerEdge XR7620
Figure 4. Rear view of Front Accessed configuration
Table 2. Features available on the Rear view of Front Accessed configuration
Item Ports, panels, and slots Icon Description
1 Cooling fan N/A Supports 6 cooling fans
NOTE: All 6 fans need to
be installed in the system
during operation.
12 System overview

System configurations - inside view for PowerEdge XR7620
Figure 5. Inside the system - Front Accessed configuration
1. Cooling fan 2. 2U air shroud
3. Intrusion switch 4. Front PERC
5. SSD backplane 6. System board
7. Drive cage 8. Expansion card riser 3
9. OCP card 10. BOSS module
11. Memory slots 12. Processor heat sink module
13. 1U air shroud
System overview 13

Rear Accessed Configuration (Normal Airflow) for
XR7620
System configurations - front view for PowerEdge XR7620
Figure 6. Front view of Rear Accessed configuration with bezel
Figure 7. Front view of Rear Accessed configuration without bezel
Table 3. Features available on the front view of Rear Accessed configuration without bezel
Item Ports, panels, and slots Icon Description
1 Status LED control panel N/A Contains the system health,
system ID, status LED.
●Status LED: Enables you
to identify any failed
hardware components.
There are five status LEDs
and an overall system
health LED (Chassis health
and system ID) bar. For
more information, see
the Status LED indicators
section.
2 Cooling fan N/A Supports 6 cooling fans.
14 System overview

Table 3. Features available on the front view of Rear Accessed configuration without bezel(continued)
Item Ports, panels, and slots Icon Description
NOTE: All 6 fans need to
be installed in the system
during operation.
3 Power button control panel N/A Contains the power button,
USB port, iDRAC Direct micro
USB port, and the iDRAC
Direct status LED.
System configurations - rear view for PowerEdge XR7620
Figure 8. Rear view of Rear Accessed 4 x 2.5-inch drive configuration without bezel
Figure 9. Rear view of Rear Accessed 8 x E3.S drive configuration without bezel
Table 4. Features available on the rear view of Rear Accessed configuration without bezel
Item Ports, panels, or slots Icon Description
1 PCIe expansion card riser 1
(slot 1)
N/A Enables you to connect PCI
Express expansion cards.
2 PCIe expansion card riser 1
(slot 2)
N/A Enables you to connect PCI
Express expansion cards.
3 PCIe expansion card riser 2
(slot 3)
N/A Enables you to connect PCI
Express expansion cards.
4 PCIe expansion card riser 2
(slot 4)
N/A Enables you to connect PCI
Express expansion cards.
5 Drive N/A Enables you to install up to 4
x 2.5-inch, or 8 x E3.S Solid-
State Drives (SSDs)
System overview 15

Table 4. Features available on the rear view of Rear Accessed configuration without bezel(continued)
Item Ports, panels, or slots Icon Description
6 Power supply unit (PSU 2)
and (PSU 1) Indicates the PSU2 (redundant PSU) and PSU1
(primary PSU)
7System identification button Press the system ID button:
●To locate a particular
system within a rack.
●To turn the system ID on
or off.
To reset iDRAC, press and
hold the button for 16
seconds.
NOTE:
●To reset iDRAC using
system ID, ensure that
the system ID button is
enabled in the iDRAC
setup.
●If the system stops
responding during
POST, press and hold
the system ID button
(for more than five
seconds) to enter the
BIOS progress mode.
8VGA port Enables you to connect a
display device to the system.
9 PCIe expansion card riser 3
(Low profile slot 5)
N/A Enables you to connect PCI
Express expansion cards.
10 OCP NIC card (optional) N/A The OCP NIC card supports
OCP 3.0. The NIC ports are
integrated on the OCP card
which is connected to the
system board.
11 USB 2.0 port This port is USB 2.0-
compliant.
12 USB 3.0 port This port is USB 3.0-
compliant.
13 iDRAC dedicated port It is an RJ-45 port.
Enables you to remotely
access iDRAC. For more
information, see the
Integrated Dell Remote
Access Controller User's
Guide at www.dell.com/
poweredgemanuals.
14 2 x LOM ports The LOM ports that are
integrated on the system
board provide network
connectivity. These LOM
ports can also be shared with
iDRAC when iDRAC network
settings is set to shared
mode.
16 System overview

System configurations - inside view for PowerEdge XR7620
Figure 10. Inside the system - Rear Accessed configuration
1. Cooling fan
2. 2U air shroud
3. Intrusion switch
4. Backplane
5. Drive cage
6. Express Service Tag
7. System board
8. Expansion card riser 3
9. OCP card
10. BOSS module
11. Memory slots
12. Processor heat sink module
13. 1U air shroud
System overview 17

Bezel view
Figure 11. Bezel for the Rear Accessed configuration
Table 5. Bezel for the Rear Accessed configuration
Item Indicator, button, or
connector
Description
1 Bezel filter Provides protection from sand and dust.
NOTE: To maintain optimal system health, Dell recommends checking and
changing the filter every three months. Filters can be ordered from Dell.
2 Bezel key lock Locking mechanism for the bezel. The bezel comes with a key.
3 Bezel LED indicator System health indicator.
4 Bezel release button When pressed, the bezel will unlock from the system.
5 Bezel filter release button Bezel filter button is pressed to release the bezel filter.
Figure 12. Bezel for the Front Accessed configuration
NOTE: Without the front bezel, Front Accessed configuration support racks with 80 mm spacing from rack ear of chassis
to inside surface of rack door. With the front bezel installed, the Front Accessed configuration system support racks with
100 mm spacing from rack ear of chassis to inside surface of the rack door
Table 6. Bezel for the Front Accessed configuration
Item Indicator, button, or
connector
Description
1 Bezel filter Provides protection from sand and dust.
NOTE: To maintain optimal system health, Dell recommends checking and
changing the filter every three months. Filters can be ordered from Dell.
18 System overview

Table 6. Bezel for the Front Accessed configuration(continued)
Item Indicator, button, or
connector
Description
2 Bezel key lock Locking mechanism for the bezel. The bezel comes with a key.
3 Bezel LED indicator System health indicator.
4 Pressure sensor Indicates when to replace the filter.
NOTE: The pressure sensor device is located behind the bezel.
5 Bezel release button When pressed, the bezel will unlock from the system.
6 Bezel filter release button Bezel filter button is pressed to release the bezel filter.
Bezel overview
Bezel filter
Figure 13. Bezel filter
The PowerEdge XR7620 has a front bezel that comes with a lock feature and a diagnostics LED. The bezel is designed with a
filter that provides protection against sand and dust.
Pressure sensor
The pressure sensor device on the front bezel is only available on the Front Accessed configuration systems. The pressure
sensor indicates when to replace the bezel filter in iDRAC. The connection between the pressure sensor with the XR7620
system is established through the POGO pin that connects the pressure sensor to the system chassis.
Filter modes
There are two filter modes available in the iDRAC when a bezel installed.
●Count Down mode
●Active Sensing mode
NOTE: Only available for the Front Accessed configuration with pressure sensor.
System overview 19

Count Down mode and Active Sensing mode is mutually exclusive, thus the user can activate either the Count Down mode or
the Active Sensing mode. Not both simultaneously in a single server. The sensor events can be enabled or disabled by using the
"Air filter alert" option. In the Active Sensing mode, the sensor events are triggered when a physical bezel is installed. The "Air
filter alert" option is disabled by default. When the option is disabled, iDRAC monitors the presence or absence of the filter. It
monitors the status of the filter.
Count Down mode
The Count Down mode works as follows:
●The alerts are sent out based on the filter life expiry date. iDRAC provides the following data for users to manage the filter:
NOTE: This mode can be used for passive or active bezel filters. It counts down when the system is switched on.
○Filter Change Interval — This attribute is configurable in months and set to 3 months by default. This option allows
users to configure filter change interval from 1 to 24 months.
○Filter Life Remaining — This attribute indicates the filter life span in days. The count down timer is activated when the
server is switched on. Once the it counts down to zero, the filter status goes to a degraded state.
○Reset Filter Life — Enable users to reset the filter life. This loads the Filter Life Remaining time with the current Filter
Change Interval time. The count down starts when the system is switched on. Enabling this option activates a system
log—BEZL0007.
●Readings and alerts:
○BEZL0003 filter dirty—indicates that a filter replacement is required. Occurs when the count down mode has reached
the time limit.
Figure 14. iDRAC interface of the Count Down mode
Active Sensing mode
The Active Sensing mode works as follows:
NOTE: This mode requires active bezel filter. An unsupported configuration indicates that the filter baseline is not
supported and generates an error log—BEZL0006.
●When enabled, the iDRAC monitors the filter pressure sensor to determine the filter status.
●Reset Filter Life — resets the filter reading and sets it as a baseline reading.
NOTE: Resets the clean filter baseline against which degradation is measured. This activates system log—BEZL0007.
●Scheduling Active Filter Check — Default Monday 3:00 AM. Fans run at full speed to get viable airflow reading. This
happens by default every Monday at 3.00am. User may change to the preferred time.
20 System overview