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Creating a Snapshot and Using It to Boot a QFX3500 and QFX3600 Series Switch

 

The system snapshot feature takes a “snapshot” of the files currently used to run the QFX Series switch—the complete contents of the /config and /var directories, which include the running Juniper Networks Junos OS, the active configuration, and the rescue configuration—and copies all of these files into an alternate (internal, meaning internal flash, or an external, meaning USB flash) memory source. You can then use these snapshots to boot the switch at the next bootup or as a backup boot option.

The system snapshot feature is especially effective as a bootup option after a partition corruption, as it is the only recovery option that allows you to completely restore the Junos OS and configuration in the event of a corrupted partition.

This topic includes the following tasks:

Creating a Snapshot on a USB Flash Drive and Using It to Boot the Switch

Note

Creating a snapshot is not supported on QFX10000 switches.

A snapshot can be created on USB flash memory after a switch is booted using files stored in internal memory.

Ensure that you have the following tools and parts available before creating a snapshot on a USB Flash drive:

To create a snapshot on USB flash memory and use it to boot the switch:

  1. Place the snapshot into USB flash memory:
    Note

    This example uses the partition option. If you have already created a partition for the snapshot, you don’t need to use the partition option.

  2. (Optional) Perform this step if you want to boot the switch now using the snapshot stored on the external USB flash drive. If you created the snapshot as a backup, do not perform this step.
    • To reboot the switch using the most recently created snapshot:

    • To reboot the switch using a snapshot in a specific partition on the USB flash drive:

Creating a Snapshot on an Internal Flash Drive and Using it to Boot the Switch

A snapshot can be created on internal memory after a switch is booted using files stored in external memory.

To create a snapshot in internal memory and use it to boot the switch:

  1. Place the snapshot files in internal memory:
    Note

    This example uses the partition option. If you have already created a partition for the snapshot, you don’t need to use the partition option.

  2. (Optional) Perform this step if you want to boot the switch now using the newly created snapshot. If you created the snapshot as a backup, do not perform this step.
    • To reboot the switch using the most recently created snapshot:

    • To reboot the switch using a snapshot in a specific partition in internal memory:

Creating a Snapshot on the Alternate Slice of the Boot Media

The alternate slice of the boot media contains a backup software image that the switch can boot from if it is unable to boot from the primary slice. When you upgrade software, the new software image gets copied only to the primary slice of the boot media.

To create a snapshot of the currently booted software image on the backup slice of the boot media:

After the system boots up, you will see the following message before the login prompt:

WARNING: THIS DEVICE HAS BOOTED FROM THE BACKUP JUNOS IMAGE

It is possible that the primary copy of JUNOS failed to boot up properly, and so this device has booted up from the backup copy.

Please re-install JUNOS to recover the primary copy in case it has been corrupted.

The system will generate an alarm indicating that the switch has booted from the backup slice.