Setting up serial logging for Linux/UNIX virtual machines
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Setting up serial logging for Linux/UNIX virtual machines


Article ID: 344274


Updated On:


VMware vSphere ESXi


This article provides steps to set up serial logging for Linux/UNIX virtual machines. Serial Logging helps to capture and redirect boot errors to a virtual serial port file for troubleshooting purposes.

You may want to set up serial logging if the kernel panic errors during the virtual machine boot process scroll too fast and you are unable to capture the errors.


VMware ESXi 3.5.x Installable
VMware ESXi 4.0.x Embedded
VMware ESXi 3.5.x Embedded
VMware ESXi 4.1.x Embedded
VMware vSphere ESXi 5.0
VMware ESXi 4.1.x Installable
VMware ESXi 4.0.x Installable


To enable serial logging:

  1. Right-click the virtual machine or virtual appliance and click Edit Settings.
  2. Click the Hardware tab and then click Add.
  3. Select Serial Port and click Next.
  4. Select Output to file and click Next.
  5. Click Browse and navigate to the virtual machine for which you want to add a serial port.
  6. In File Name, type SerialOutput and click OK.
  7. Under Device Status, select Connect at power on and click Next > Finish.
  8. Click the Options tab.
  9. Click Boot Options and enter 10,000 in Power On Boot Delay.
  10. Click OK.
  11. Power on the virtual machine. The virtual machine waits for 10 seconds before it begins to load the operating system.
  12. After the operating system loads (a blue background loads), you see this line on top of the screen:

    Press any key to enter the Boot menu

  13. Press the Space Bar to enter into the GNU GRUB.
  14. Select the operating system, such as CentOS (2.6.18-164.9.1.el5), and press e to modify the grub options.
  15. Use the down arrow key to select the line:

    kernel /vmlinuz-2.6.78-164.9.1.el5 ro root=LABEL=10 console

  16. Press e to append this line:

    console=tty0 console=ttyS0,115200

  17. Press Enter to commit the changes.
  18. Press b to boot into the grub.
  • After a boot failure, power on the virtual machine, log in to the host that manages the virtual machine, and navigate to the home directory. You should see a file named SerialOutput, which is the new Serial Logging log.
  • For information on collecting and uploading a support bundle to VMware, see Collecting diagnostic information for VMware ESX/ESXi (653).

Additional Information

Collecting diagnostic information for VMware ESX/ESXi