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SRX Getting Started - Junos Software Installation/Upgrade



Article ID: KB16652 KB Last Updated: 30 Jan 2021Version: 41.0

This article documents how to install or upgrade Junos software on SRX devices.

For other topics, go to the SRX Getting Started main page.

  • Install Junos software on the SRX device.
  • Upgrade Junos software on the SRX device.

This sections contains the following:

Download Software from Support site

Download Junos software and Release Notes for your SRX product.  Select the product from Software Downloads - SRX Series

Useful links:

Software Installation Preparation

  1. Read the Release Notes, as they document new features, changes in default behavior, known limitations, and issues. A copy of the Release Notes is in the product documentation, under the specific product name.

  2. Set up your connection to the SRX to log your session during the installation and through the reboot, as the transcript can provide valuable information if an issue happens and JTAC needs to review it. 

  3. Confirm there are no uncommitted changes present because candidate changes are usually lost on a reboot. Enter the command:

    user@srx# top
    user@srx# show | compare

    If the command contains configuration information that you want to keep, then perform a commit.

  4. Back up your configuration, by logging your session while performing the following command.  Keep it in a safe place.

    user@srx> show configuration | no-more
  5. If you want to back up the current Junos and configuration onto media (such as a USB/CF) so that it can be put back into the SRX if the SRX does not boot up and allow the SRX to boot up, refer to the following instructions: Backing Up the Current Installation.

    For example:

    a. Prepare USB Stick: KB12880-How to mount a USB drive on the EX/SRX/MX/QFX series platforms
    b. Save a snapshot from a running SRX to the USB Stick.  Use the command: request system snapshot media usb                                                 
  6. If you are going to do a J-Web installation or copy the Junos software image to the SRX, then check the flash size and purge unused files:

    Check current Flash size:

    show system storage | match cf

    Purge logfiles:

    request system storage cleanup      

    If Flashsize is still lower than the size of your image, then try the following:

    • Clear files from the /var/log directory.  Clear or remove any traceoptions files and clear any log files which are not needed.  Note that you will lose all contents of the log file after a clear is done.
      clear log <log-filename>
    • Purge software backup.  Note that if you delete the backup software, you will not be able to rollback using the "request system software rollback" command.
      request system software delete-backup
    • Locate directories on the flash with large amount of data.
      show system directory-usage /cf          
    • To save space browse directories and erase files manually:  Be careful with which file you choose to delete.
      file list /var/tmp
      file delete /var/tmp/xyz

    If you cannot free up enough space, then refer to KB19466 - Common and safest files to remove in order to increase the system storage OR use CLI Installation Method 2 or 3 below. 

Note: For a Chassis cluster installation, a SRX device with Redundant Routing Engines (JSRP), it is recommended to use CLI Installation Method 1 or 2. In Chassis cluster installation when the request system reboot command is executed it only affects the node on which this command is run. Both nodes of the cluster need to use the same hardware and release. In case of Chassis cluster upgrade we recommend to upgrade both the nodes followed by a reboot at the same time.

Install Software via CLI (Method 1 - from Junos software copied to SRX)

Follow these steps to copy the software to the SRX device and then perform the software installation via the CLI:

  1. Copy software to SRX via SCP or FTP to /var/tmp: 

    For example:

    user@srx>  scp  username@<ip address of local scp server>:junos-srxsme-12.1X46-D40.2-domestic.tgz  /var/tmp/junos-srxsme-12.1X46-D40.2-domestic.tgz


    user@srx>  ftp <ip address of local ftp server>  (and login)
    user@srx>  lcd /var/tmp/
    user@srx>  bin
    user@srx>  get junos-srxsme-12.1X46-D40.2-domestic.tgz
    user@srx>  bye
  2. Install software with the commands below.  For detailed instructions, refer to Installing the Software.

    For example:

    From the local file in /var/tmp

    user@srx>  request system software add no-copy /var/tmp/junos-srxsme-12.1X46-D40.2-domestic.tgz
    user@srx>  request system reboot

Install Software via CLI (Method 2 - from Junos software on FTP server)

In order to perform the software installation from the CLI via the software on a FTP server, follow the instructions at Installing the Software EXCEPT use the syntax in these examples for the 'request system software' commands:

Two examples:

  • Fetch from a FTP Server (user username), then reboot after update.

    The no-copy option is used to save space.

    user@srx>  request system software add no-copy ftp://username:password@
    user@srx>  request system reboot
  • Same example fetching from a FTP server with user anonymous.

    If validation of configuration reports that your current config is not working with the new release (e.g. on downgrade), you can bypass this with the no-validate option.

    user@srx>  request system software add no-copy no-validate
    user@srx>  request system reboot

Install Software via CLI (Method 3 - from Junos software copied to USB stick)

Follow these steps to install the software via the CLI from a USB stick:

  1. Download the Junos upgrade file to the USB stick. 
  2. Locate the USB device ID that Junos is associating to the USB stick:

    user@srx> start shell
    user@srx% ls /dev/ > /var/tmp/before_USB.txt
  3. Insert the USB device into the USB slot.  For example, slot 0 would return the following:
    root# umass0: USB USBFlashDrive, rev 2.00/1.00, addr 2
    da0 at umass-sim0 bus 0 target 0 lun 0
    da0: <USB USBFlashDrive 0100> Removable Direct Access SCSI-0 device
    da0: 1.000MB/s transfers
    da0: 980MB (2007040 512 byte sectors: 64H 32S/T 980C)

    Run the following command:

    user@srx% ls /dev/ > /var/tmp/after_USB.txt

    Locate difference in the "before_USB.txt" and "after_USB.txt" outputs to locate drive label by using the "diff" command. (It will usually be da#s1, i.e. da0s1)

    user@srx% diff /var/tmp/before_USB.txt /var/tmp/after_USB.txt
    > da1
    > da0s1
    > pass1

    In this example the USB is "da0s1".

  4. Create a mount directory:
    user@srx% mkdir /tmp/usb
  5. Mount the USB to the directory:
    user@srx% mount -t msdosfs /dev/<drivelabel> /tmp/usb


    user@srx% mount -t msdosfs /dev/da0s1 /tmp/usb (there is a space between the label name and /tmp)

    Verify that the USB is mounted to the device:

    root@% pwd
    root@% cd /tmp/usb/
    root@% pwd
    root@% ls
  6. Exit shell and install the software:
    user@srx% exit
    user@srx> request system software add /tmp/usb/<upgrade filename> no-copy

    For additional details regarding a software installation, refer to the instructions at Installing the Software.

  7. Upon completion, reboot the SRX:

    user@srx> request system reboot

Install Software via J-Web

Software installation via J-Web is the simplest of these procedures. However, it does require a minimum of 512MB compact flash and it is slower than the CLI methods.  Refer to these steps to install the software via J-Web:

  1. Select Maintain > Software > Upload Package.
  2. Specify the 'File to Upload.'
  3. Click Upload and Install Package to perform the installation.

For additional details regarding a software installation, refer to J-Web Interface User Guide [PDF] or J-Web Interface User Guide [HTML] .

Install Software via Bootloader

In the case that the kernel does not boot, either of these procedures can be performed to do an emergency software installation on SRX series devices:

Note: The KB's below are valid only for Branch SRX devices. As of now, high-end SRX devices DO NOT support USB or TFTP installs from the loader.

Other Installation Methods

For additional installation methods, refer to the following:

Technical Documentation

For additional information not covered in this article, refer to the technical documentation:

Note: Select your Junos version from the pull-down list near the top of the page.

Modification History:
2021-01-30: Changed USB to all caps state, to keep command syntax consistent.
2020-09-17: Updated J-web pdf and html links, removed paragraph for older software not on download site, as that URL link is no longer available. Changed KB21476 to reflect correct title.
2020-02-04: Updated references for J-series
2019-06-26: Corrected the SCP command syntax under Method 1
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