Description

How to load primary or secondary partition in loader prompt.

Symptoms

The Junos software loads but the CLI is not working or the switch may have file system corruption.

Solution

  • File system corruption
  • Power outage
  • Multiple reboots

Setting the boot partition:

The system disk has two partitions and can have a different software package installed in each partition. You can manually reset the system to boot from the other partition. You can set the system to boot from the other partition on the next reboot only, or make the change permanent so that it will boot from the other partition on all subsequent reboots.

To specify reboot from the partition that is not currently active for the next reboot only, issue the following commands from within the loader.

Example: 

unload 
unset vfs.root.mountfrom
set currdev=disk0S<disk-number>:
boot

Where disk-number indicates the partition number, either 1 or 2 . 

unload 
unset vfs.root.mountfrom
set currdev=disk0S2:
echo $currdev
boot

To reset the partition that is designated the active partition, exit the CLI and enter the following commands from the UNIX prompt: 

# echo "a<disk-number>" |fdisk –f –/dev/da0
# reboot
Where disk-number indicates the partition number, either 1 or 2.

Once the system boots up, you can try to see if you can try to perform a system snapshot to copy from the partition you boot it and to the other partition disk. 

      request system snapshot slice alternate

Modification History

2020-07-02: Updated entire article.