This article provides frequently asked questios about the Resilient dual-root Partitioning feature, introduced in Junos OS 10.4R3, 11.1R1 and all later releases.

Note : This FAQ article will be periodically updated to reflect any changes between releases.

Starting with Junos Software Release 10.4R3 and 11.1R1, the EX Switch File System will be formatted from a 3 slice partition to a 4 slice partitioning scheme. This is related to the Resilient dual-root Partition feature that was introduced in these releases and all later releases.

There are certain upgrade requirements that are documented in the Junos Release Notes and Junos Software Guide for the EX Switch Platform, starting with Junos Software releases 10.4R3 and 11.1R1. The information listed here should provide additional detail or common links to this information and assist with EX Switch upgrades for all platforms.

1. EX Switches - What are the File System differences between Junos 10.4R2 and earlier releases, compared to 10.4R3 and all later Junos releases? (From 10.4R3 Release Notes)
2. What are the requirements for upgrading from Junos OS 10.4R2 and any later release (10.4R3, 11.1R1 and all later releases)? What documentation is available?
3. How Does Upgrading to Junos OS Release 10.4R3 and Later Differ from Normal Upgrades?
4. Can I Downgrade Junos OS Without Downgrading the Loader Software?
5. Will I Lose My Configuration During an Upgrade from Junos OS 10.4R2 (or earlier release), to Junos OS 10.4R3 (or later release)?
6. Can I Upgrade to a Resilient Dual-Root Partition Release by Using the CLI?
7. How Long Will the Upgrade Process Take?
8. What Happens If I Do Not Upgrade Both the Loader Software and Junos OS at the Same Time?
9. What Happens to My Files If the System Detects a File System Corruption?
10. How Will I Be Informed If My Switch Boots from the Alternate Slice Due to Corruption in the Root File System?
11. Can I Use Automatic Software Update and Download to Upgrade to a Resilient Dual-Root Partition Release?
12. Why is the Message "At least one package installed on this device has limited support" Displayed When Users Log in to an EX8200 Switch?
13. Where can I download the Jloader images and what are the required installation package names?
14. How do I verify the Junos images installed on each partition/slice? Are there CLI commands to verify what Junos versions are installed on each slice (S1 and S2)?
15. How do I determine or verify the loader version installed?
16. Will a format take place each time I upgrade Junos on my EX Switches after I upgrade to release 10.4R3/11.1R1 or any later Junos Release?
17. What if I am running Junos 10.4R3 and upgrade to Junos 11.1R1 (both new 4 slice partitions)?
18. What CLI or shell commands are available for checking the file system, slices, etc?
19. What happens if an ungraceful shutdown, reboot, or power outage happens and EX Switch does or does not detect a failure during boot up? (NOTE: This is with boot-sequence ENABLED - resiliency variable set to enable)
20. What is the recommended upgrade path to any release starting with 10.4, if I am running any Junos 9.x release?
21. Why does Jloader installation fail with error message, "Installation failed with exit status 1", while installing Jloader on EX Switch running 9.x? Jloader installs fine when EX Switch is running Junos OS 10.x or later Junos OS release.

1. EX Switches - What are the File System differences between Junos 10.4R2 and earlier releases, compared to 10.4R3 and all later Junos releases? (From 10.4R3 Release Notes)
   
   Resilient Dual-Root Partition Scheme (Junos OS Release 10.4R3 and Later)
   EX Series switches that ship with Junos OS Release 10.4R3 or later are configured with a root partition scheme that is optimized for resiliency, as shown in Table below (see Release Notes for additional detail).
   
   10.4R3 and all later Junos Releases for EX Switches
   
   
   
   In the resilient dual-root partition scheme, the /var file system is contained in a separate slice from the root file systems, the /config directory is contained in its own slice, and switches ship from the factory with identical Junos OS images in slice 1 and slice 2. The /var file system, which has a greater frequency of reads and writes than the root file systems and is therefore more likely to have corruption issues, is isolated from the root directories and the /config directory. If the switch fails to boot, the system automatically boots from the alternate root partition. (If the switch fails to boot from the active root partition and instead boots from the alternate root partition, an alarm is triggered.).
   
   
   Earlier Partition Scheme (Junos OS Release 10.4R2 and Earlier)
   
   
   
   
   This is the partitioning scheme for a switch shipped with Release 10.4R2 or earlier (or after you reformat the disk during a downgrade from Release 10.4R3 or later to Release 10.4R2 or earlier). In this partitioning scheme, the switch comes from the factory with only one Junos OS image installed in the root Junos OS partition of slice 1. The first time that you perform a software upgrade, the new Junos OS image is installed in slice 2. If the switch fails to boot, you must manually trigger it to boot from the alternate partition (rebooting from the alternate partition does not occur automatically).
2. What are the requirements for upgrading from Junos OS 10.4R2 and any later release (10.4R3, 11.1R1 and all later releases)? What documentation is available?
   
   
   Note : See section "Understanding Resilient Dual-Root Partitions on Switches - Resilient Dual-Root Partition Scheme (Junos OS Release 10.4R3 and Later)".
   • The Release Notes in 10.4 and 11.1 include the upgrade instructions for each platform. See section "Upgrade and Downgrade Instructions for Junos OS Release 11.1 for EX Series Switches".
   • PSN-2011-03-201 provides additional details concerning this feature release and also the Jloader images for each platform.
   • PSN-2011-03-201 Feature Release “Resilient Dual-Root Partitions” for EX Series Switches - (Junos OS Release 10.4R3 and later)
     Company header - View JTAC Technical Bulletin
   • Junos 10.4 Release Notes:
     Junos US/Canada 10.4
   • Junos 11.1 Release Notes:
      Junos US/Canada 11.1
   • Junos 11.1 EX User Guide:
     Complete Software Guide for Junos® OS for EX Series Ethernet Switches, Release 11.1
3. How Does Upgrading to Junos OS Release 10.4R3 and Later Differ from Normal Upgrades?
    
   • Upgrading from Junos OS Release 10.4R2 or earlier to Release 10.4R3 or later differs from other upgrades in these ways:
   • 10.4 Release Note:
     NOTE : If you are upgrading from Release 10.4R2 or earlier, the addition of the new resilient dual-root partitions feature requires that you install new loader software as part of the upgrade process. This special software upgrade takes a little more time to complete than a standard upgrade. See Release Notes - “Upgrade and Downgrade Instructions for Junos OS Release 10.4 for EX Series Switches” for information about how to upgrade to Release10.4R3.
   • Rebooting for the Junos Software upgrade reformats the disk from three partitions to four partitions.
   • The upgrade process and the reboot take longer due to the additional time required to upgrade the loader software and additional time for the first reboot after the Junos OS installation (longer than normal because it reformats the disk from three partitions to four). Also, EX8200 switches require an additional reboot per Routing Engine as part of the loader software upgrade.
4. Can I Downgrade Junos OS Without Downgrading the Loader Software?
   
   
   NOTE - The latest jloader is not supported in releases prior to 10.0R1 (Junos 9.x Releases)
   • To downgrade to Release 10.4R2 or earlier without downgrading the loader software, you must disable the boot-sequencing function. Because earlier Junos OS releases do not contain the newer settings, the switch will boot on each subsequent reboot from the alternate root partition rather than from the active partition. If you disable the boot-sequencing function, you can run Release 10.4R2 or earlier with the new loader software and have no adverse effects.
     
     Disable the boot-sequencing function in one of two ways:
      
     •  From the shell as user root:
       % nvram setenv boot.btsq.disable 1
     • From a console connection, reboot and stop at the u-boot prompt (Ctrl-C):
       => setenv boot.btsq.disable 1 => savenv
5. Will I Lose My Configuration During an Upgrade from Junos OS 10.4R2 (or earlier release), to Junos OS 10.4R3 (or later release)?
    
   • The configuration files in /config are saved in volatile memory before the reformat and then restored after the reformat—however, the files in /var are not saved and are lost after the upgrade.
   • Note : We recommend that you copy your data files to external media using the request system snapshot command before you perform the upgrade. Files in the /var directory, such as log files and user /home directories, are not saved. In addition, a power failure during the reboot could cause the configuration files to be lost.
6. Can I Upgrade to a Resilient Dual-Root Partition Release by Using the CLI?
   
   Yes, you can perform the entire upgrade to resilient dual-root partitions from the CLI. You download both the new loader software and Junos OS packages and install them from the CLI. During the final reboot, the disk is automatically reformatted from three partitions to four partitions.
7. How Long Will the Upgrade Process Take?
   
   The process of upgrading to a resilient dual-root partitions release takes longer due to the additional step of upgrading the loader software and a longer reboot time while the disk is reformatted to four partitions during the reboot of the switch that completes the Junos OS upgrade. The reformat increases the reboot time for EX2200, EX3200, EX4200, and EX4500 switches by 5 to 10 minutes. For EX8200 switches, the reboot time increases by 10 to 25 minutes per Routing Engine, and additional reboots are required.
8. What Happens If I Do Not Upgrade Both the Loader Software and Junos OS at the Same Time?
   
   You must install a new loader software package if you are upgrading to a release that supports resilient dual-root partitions (Release 10.4R3 and later) from an earlier release (Release 10.4R2 and earlier). (See 10.4 or 11.1 Release Notes for additional details).
   
   
   
   
   
9. What Happens to My Files If the System Detects a File System Corruption?
   
   During a reboot, the system checks each file system partition for corruption. The action the system takes if corruption is detected and the corrective action that you can take. (See 10.4R3 Release Notes Link Below)
   
   
10. How Will I Be Informed If My Switch Boots from the Alternate Slice Due to Corruption in the Root File System?
    
    If the switch detects corruption in the primary root file system, it boots from the alternate root partition. When this occurs, you are notified in two ways:
     
    • If you are logged in through the console port or the management port:
      
      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 from the backup copy. Please re-install JUNOS to recover the primary copy in case it has been corrupted.
    • The following alarm message is generated:
      
      user@switch> show chassis alarms
      1 alarms currently active
      Alarm time Class Description
                      2011-02-17 05:48:49 PST Minor Host 0 Boot from backup root
11. Can I Use Automatic Software Update and Download to Upgrade to a Resilient Dual-Root Partition Release?
    
    Automatic software update and automatic software download are both supported with upgrading to resilient dual-root partition releases. However, after an automatic installation, you must take the extra step of upgrading the loader software.
    
    Automatic software update is for new members added to a Virtual Chassis that do not have the same software as the primary. Once this feature is configured on the Virtual Chassis, any new member added with a different software version will be upgraded automatically.
    
    Automatic software download uses the DHCP message exchange process to download and install software packages.
12. Why is the Message "At least one package installed on this device has limited support" Displayed When Users Log in to an EX8200 Switch?
    
    The following message might be displayed when a user logs in to an EX8200 switch:

    Logging to master
..Password:
--- JUNOS 10.4R3.4 built 2011-03-19 22:06:32 UTC
    
    At least one package installed on this device has limited support.
    Run 'file show /etc/notices/unsupported.txt' for details.

    • This message can be safely ignored or you can permanently remove it. It appears because of the jloader package file detected on system, and only appears when the Junos OS software is installed before upgrading the loader software, which is the case only for EX8200 switches.
    • You can permanently remove this message by removing the jloader package and rebooting the system:
      request system software delete jloader-ex-8200-11.3-date-domestic-signed.tgz
      request system reboot

13. Where can I download the Jloader images and what are the required installation package names?
     
    • The Jloader images for each EX Switch platform are NOT available on the Junos Software Download Site. The Jloader images are available via PSN-2011-03-201
      
      Feature Release “Resilient Dual-Root Partitions” for EX Series Switches - (Junos OS Release 10.4R3 and later)
      View JTAC Technical Bulletin - PSN-2011-03-201
    • Note : To obtain the loader software package: see the Download Software page at Junos US/Canada Download Software . Click on the version, then the Software tab, then the name of the software install package. In the pop-up Alert box, click on the link to the PSN document.
    • Required Installation Packages for Upgrading the Loader Software
      
      
14. How do I verify the Junos images installed on each partition/slice? Are there CLI commands to verify what Junos versions are installed on each slice (S1 and S2)?
    
    Yes. Please use the "show system snapshot media internal slice" command for each slice.

    root> show system snapshot media internal slice 1

Information for snapshot on internal (/dev/da0s1a) (primary)
Creation date: May 2 16:38:06 2011
JUNOS version on snapshot:
jbase : 10.4R3.4
jcrypto-ex: 10.4R3.4
jdocs-ex: 10.4R3.4
jkernel-ex: 10.4R3.4
jroute-ex: 10.4R3.4
jswitch-ex: 10.4R3.4
jweb-ex: 10.4R3.4
jpfe-ex82x: 10.4R3.4

root> show system snapshot media internal slice 2
Information for snapshot on internal (/dev/da0s2a) (backup)
Creation date: May 2 16:35:55 2011
JUNOS version on snapshot:
jbase : 10.4R3.4
jcrypto-ex: 10.4R3.4
jdocs-ex: 10.4R3.4
jkernel-ex: 10.4R3.4
jroute-ex: 10.4R3.4
jswitch-ex: 10.4R3.4
jweb-ex: 10.4R3.4
jpfe-ex82x: 10.4R3.4

15. How do I determine or verify the loader version installed?
    
    Use the “show chassis firmware” command to verify the jloader version. Determine the version of the loader software:

    user@switch> show chassis firmware
    Part 		Type 		Version
    FPC 6 		U-Boot 		U-Boot 1.1.6 (Jan 13 2009 - 06:55:22) 2.3.0
                    loader 		FreeBSD/PowerPC U-Boot bootstrap loader 2.2
    FPC 7 		U-Boot 		U-Boot 1.1.6 (Jan 13 2009 - 06:55:22) 2.3.0
                    loader 		FreeBSD/PowerPC U-Boot bootstrap loader 2.2
    Routing Engine 0 U-Boot 	U-Boot 1.1.6 (Mar 2 2011 - 04:29:01) 3.5.0
                    loader		 FreeBSD/PowerPC U-Boot bootstrap loader 2.3
    Routing Engine 1 U-Boot 	U-Boot 1.1.6 (Mar 2 2011 - 04:29:01) 3.5.0
                    loader 		FreeBSD/PowerPC U-Boot bootstrap loader 2.3
    

16. Will a format take place each time I upgrade Junos on my EX Switches after I upgrade to release 10.4R3/11.1R1 or any later Junos Release?

     

    No. An automatic format only takes place when you upgrade from Junos OS 10.4R2, or any earlier release (3 slice partition), to 10.4R3/11.1R1 or any later Junos release.

17. What if I am running Junos 10.4R3 and upgrade to Junos 11.1R1 (both new 4 slice partitions)?
     
    • Since you already went through the formatting process when upgrading to 10.4R3 there will be no formatting done when upgrading to 11.1R1.
      
      However, the Junos 11.1R1 image is only installed on the other slice so you have to copy the 11.1R1 image to the alternate slice after upgrading to 11.1R1. You can do this by using the snapshot command "request system snapshot media internal slice alternate". (See Release Note listed below)
      
      This will copy the image from active slice (running 11.1R1) to the alternate slice and ensure that you have full resiliency.
    • Junos 10.4 and 11.1 Release Notes:
      For the upgrade to Release 10.4R4, the upgrade process automatically copies the contents of the primary root partition to the alternate root partition at the end of the upgrade process. Because the resilient dual-root partitions feature enables the switch to boot transparently from the alternate root partition, we recommend that you use the request system snapshot command to copy the contents of the primary root partition to the alternate root partition after all future Junos OS upgrades.
18. What CLI or shell commands are available for checking the file system, slices, etc?
     
    • show system snapshot media internal slice 1
show system snapshot media internal slice 2
show system snapshot media internal slice alt
      • This command displays the Junos image installed on each slice. If you have a different version on alternate slice you should use the "request system snapshot media internal slice alternate" so both slices/partitions have same Junos image.
      • This command is not supported from Junos 12.1 onwards on EX switches. The alternate command that is supported by EX switch is as below:
        • show system snapshot media internal
    • request system snapshot media internal slice alternate
      • Introduced in 10.4R3 this command copies an image from one slice to another so both slices/partitions have same Junos image. This command is used after upgrading to sync images on alternate slice.
      • This command is not supported from Junos 12.1 onwards on EX switches. The alternate command that is supported by EX switch is as below:
        • request system snapshot slice alternate
    • request system reboot slice 1
request system reboot slice 2
request system reboot alternate
      • The above commands allows the user to boot from a specific slice.
19. nvram setenv boot.btsq.disable 0 ( ENABLES boot-sequence function for resiliency-Shell Cmd) nvram setenv boot.btsq.disable 1 ( DISABLES boot-sequence function and no resiliency)
    Note: It is NOT recommended to disable this variable if running Junos OS 10.4R3 or later release.
    • This shell command either ENABLES or DISABLES boot-sequence resiliency. If this is disabled you do not have resiliency so additional file system checks during boot sequence will not be done.
20. show system storage partitions
    • This command will tell the user whether the EX Switch is running on 'active' or 'alternate' root file system.
21. What happens if an ungraceful shutdown, reboot, or power outage happens and EX Switch does or does not detect a failure during boot up? (NOTE: This is with boot-sequence ENABLED - resiliency variable set to enable)
    
    See FAQ number 9 “What Happens to My Files If the System Detects a File System Corruption?
22. What is the recommended upgrade path to any release starting with 10.4, if I am running any Junos 9.x release?
    
    The recommended upgrade path from any 9.x release to 10.4, or any later release, is to do an incremental upgrade to Junos 10.0S13 and then 10.4R3 or 11.1. This is typical recommendation for Junos Release upgrades.
    
    Note : The new Jloader (name) will not install if EX Switch is running any Junos OS 9.x release.
23. Why does Jloader installation fail with, "Installation failed with exit status 1", while installing jloader on EX Switch running Junos OS 9.x? Jloader installs fine when EX Switch is running Junos OS 10.x, or later Junos OS release.
    
    Problem:
    Jloader fails during installation with EX Switch running Junos OS 9.x. The following error is displayed:
    
    root@ex-switch> request system software add /var/tmp/jloader-ex-3242-11.3I20110326_0802_hmerge-signed.tgz
Checking pending install on fpc0
Validating on fpc0
Done with validate on all virtual chassis members

fpc0:
Verified jloader-ex-3242-11.3I20110326_0802_hmerge.tgz signed by PackageDevelopment_11_3_0 Pre-checking requirements for jloader-ex-3242...
Auto-deleting old jloader-ex-3242...
Unmounted /packages/mnt/jloader-ex-3242-11.3I20110326_0802_hmerge ...
Adding jloader-ex-3242...
Installation in progress, please wait...
Mounted jloader-ex-3242 package on /dev/md10...
Verified manifest signed by PackageDevelopment_11_3_0 Registering jloader-ex-3242 as unsupported
/usr/libexec/ld-elf.so.1: Shared object "libgcc.so.1" not found, required by "bootupgrade"
Installation failed with exit status 1
Saving package file in /var/sw/pkg/jloader-ex-3242-11.3I20110326_0802_hmerge-signed.tgz ...
Saving state for rollback ...
    
    Solution :
    
    The Jloader cannot be installed if the EX Switch is running Junos OS 9.x. The Jloader is supported only from 10.x releases, and can be installed, only if running Junos OS 10.x or later releases.

2020-07-23: Removed broken link.

• [KB21119] EX Switch - Jloader fails during installation when EX Switch is running Junos OS 9.x [juniper.net]
• [KB21424] EX Switch Jloader fails during installation with error "verify-sig: cannot validate ./certs.pem" - If the date on an EX Switch is set to a date earlier than the date on which the jloader was built, the jloader upgrade will fail. [juniper.net]
• [KB21789] Jloader upgrade fails if running any JunOS 10.2 release on the EX2200 and EX4500 platforms only [juniper.net]