6.7

Table Of Contents
port, the request is ignored. Dynamic switching eliminates the need to interrupt the boot process manually
or to create a custom image to redirect to a serial port. It also addresses supportability issues regarding
headless systems that only have one serial port, by making it possible to switch the serial port between
different modes of operation.
ESXi Serial Port Modes
ESXi supports four serial port modes.
There are four serial port modes in ESXi:
Logging mode – Logging mode is the default mode in a debug build. Logging mode sends the
vmkernel.log over the serial port.
GDB mode – Use GDB mode for dedicated debugging.
Shell mode – Shell mode is the shell port access, which is similar to SSH.
DCUI mode – DCUI mode is a Direct Console User Interface. This is the user interface that is displayed
when you boot ESXi using a monitor.
Note Only COM1 and COM2 ports are supported. USB serial or PCI serial cards are not supported.
Dynamic Switching Keystrokes
ESXi includes a unique keystroke sequence that allows dynamic serial mode switching.
Dynamic Switching Keystrokes
Once the correct keystroke sequence is entered, the system switches the serial port to the desired mode.
Logging mode: Ctrl+G, Ctrl+B, 1
Shell mode: Ctrl+G, Ctrl+B, 2
DCUI mode: Ctrl+G, Ctrl+B, 3
GDB mode: Ctrl+G, Ctrl+B, ?
Note Once in GDB mode, you cannot switch modes again using a key sequence. You must use the CLI
to switch modes.
Serial Port Dynamic Switching Using the CLI
You can switch serial modes using the CLI.
Dynamic Switching Using the CLI
Use esxcfg-advcfg to set the current mode to none. Then set the new desired mode using the CLI.
Logging mode: esxcfg-advcfg -s com1 /Misc/LogPort
Shell mode: esxcfg-advcfg -s com1 /Misc/ShellPort
vCenter Server and Host Management
VMware, Inc. 191