Creating an Emergency Boot Device for Routing Engines with VM Host Support
If Junos OS on your device is damaged during loading in a way that prevents it from loading completely, you can use the emergency boot device to revive the device. The emergency boot device repartitions the primary disk and reloads a fresh installation of Junos OS. For RE-MX-X6, RE-MX-X8, RE-PTX-X8, and RCBPTX Routing Engines, you can use a USB storage device with at least 8 GB of free space to create an emergency boot device.
To create an emergency boot device on a device with RE-MX-X6, RE-MX-X8, RE-PTX-X8, RCBPTX, RE-QFX10002-60C, and RE-PTX10002-60C Routing Engines:
- Copy the installation media into the device’s
- Insert the USB storage device into the device’s USB port.
- In the UNIX shell, navigate to the
- Log in as su:
Super User (su) is one of the predefined login classes with preset permissions.
password: [enter SU password]
- Gunzip the copied file.
For example, to convert junos-vmhost-install-usb-mx-x86-64-15.1F6.8.img.gz to junos-vmhost-install-usb-mx-x86-64-15.1F6.8.img, , use the following command: gunzip junos-vmhost-install-usb-mx-x86-64-15.1F6.8.img.gz
- Issue the following command:
dd if=/path/to/downloaded.img of=/dev/devicenode bs=4M
devicenode—Refers to the name of the removable media of the emergency boot device. For names of storage media, see Routing Engines and Storage Media Names (ACX Series, M Series, MX Series, PTX Series, T Series, TX Matrix, TX Matrix Plus, and JCS 1200 Routers).
downloaded.img—Refers to the installation media copied to the
/var/tmpdirectory. For example,
The following code example can be used to create an emergency boot device by using a USB storage device:
dd if=/path/to/junos-vmhost-install-usb-mx-x86-64-15.1F6.8.img of=/dev/da0 bs=4M
In the dd command, use junos-vmhost-install-usb-mx-86 for RE-MX-X6 and RE-MX-X8 Routing Engines and junos-vmhost-install-ptx-86 for RE-PTX-X8 Routing Engine respectively.
- Log out as su: