Support Support Downloads Knowledge Base Juniper Support Portal Community

Knowledge Base

Search our Knowledge Base sites to find answers to your questions.

Ask All Knowledge Base Sites All Knowledge Base Sites JunosE Defect (KA)Knowledge BaseSecurity AdvisoriesTechnical BulletinsTechnotes Sign in to display secure content and recently viewed articles

[MX/PTX] How to perform system reinstall with USB emergency boot media on VMHOST platform



Article ID: KB34713 KB Last Updated: 17 Sep 2020Version: 3.0

This article explains how to reinstall or recover the system with USB Emergency Boot Device on VMHOST platforms.


Regarding 'How to create', please refer to the following link to prepare a bootable USB memory stick:

Installation images are available for each platform:

  • junos-vmhost-install-usb-mx-x86-64-18.4R1.8.img
  • junos-vmhost-install-usb-ptx-x86-64-18.4R1.8.img
  • junos-vmhost-install-usb-qfx-x86-64-18.4R1.8.img

If you are unsure which image to use, refer to KB33703 - Supported Junos Images on VMhost (Nextgen Routing Engine, x86 CPU based hardware)

Set bootable USB stick to the target device, then restart the device. Unlike non-VMHOST rounting-engine, VMHOST system cannot be restarted with 'request system reboot' command in Junos CLI. The Junos system runs over host Linux system upon VMHOST platform, therefore it requires entire system restarting so that USB boot loader can start.

To restart the host system, you have the following options:

  1. Issue 'request vmhost reboot usb' command. This command was introduced in each platform, but the corresponding first version is different. Refer to the technical document on request vmhost reboot

  2. Login to host Linux system and issue 'reboot' command.

    Example for MX-series platform with RE-MX-X6(RE-S-2X00x6):

    lab@mx240-NG-RE-re0> start shell user root


    root@mx240-NG-RE-re0:/var/home/lab # rsh -JU __juniper_private5__

    root@mx240-NG-RE-re0:/var/home/lab # reboot


    root@mx240-NG-RE-re0:/var/home/lab # shutdown -r now
  3. Power cycle manually.

    During restart, your some screen will look similar to this.  Select the appropriate line. (Some platforms may display a slightly different screen or description.)

    Select USB as boot device:

    Select 'install Juniper Linux':
Modification History:
2020-09-17: Corrected the option string in 'request vmhost reboot usb'.
Comment on this article > Affected Products Browse the Knowledge Base for more articles related to these product categories. Select a category to begin.

Getting Up and Running with Junos

Getting Up and Running with Junos Security Alerts and Vulnerabilities Product Alerts and Software Release Notices Problem Report (PR) Search Tool EOL Notices and Bulletins JTAC User Guide Customer Care User Guide Pathfinder SRX High Availability Configurator SRX VPN Configurator Training Courses and Videos End User Licence Agreement Global Search