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[MX] Understanding 'show vmhost version' command output

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Article ID: KB37001 KB Last Updated: 24 May 2021Version: 1.0
Summary:

This article discusses the 'show vmhost version' command output, such as 'boot disk' , 'root set' and 'version sets'.

Solution:

For the command 'show vmhost version', the output highlighted in blue will be explained in detail.

user@mx-re0> show vmhost version re0   
re0:
--------------------------------------------------------------------------
Current root details,           Device sda, Label: jrootb_P, Partition: sda4
Current boot disk: Primary
Current root set: b
UEFI    Version: NGRE_v00.53.00.01

Primary Disk, Upgrade Time: Thu Apr  1 20:47:54 IST 2021

Version: set p
VMHost Version: 3.1459
VMHost Root: vmhost-x86_64-17.3R3-S3-20190110_0023_builder
VMHost Core: vmhost-core-x86_64-17.3R3-S5-20190708_0008_builder
kernel: 3.10.100-ovp-rt110-WR6.0.0.31_preempt-rt
Junos Disk: junos-install-mx-x86-64-17.3R3-S5.2

Version: set b
VMHost Version: 3.1465
VMHost Root: vmhost-x86_64-17.3R3-S8-20200319_0024_builder
VMHost Core: vmhost-core-x86_64-17.3R3-S11-20210118_2225_builder
kernel: 3.10.100-ovp-rt110-WR6.0.0.31_preempt-rt
Junos Disk: junos-install-mx-x86-64-17.3R3-S11.4

  1. Current boot disk: Primary

    NG-RE has two disks: disk1 and disk2. Disk1 is considered primary and disk2 is backup.
    Boot disk = Primary == disk1
    Boot disk = Secondary == disk2
    The RE by default boots up in disk1

    The RE can be booted in disk2 using the below CLI command:

    request vmhost reboot disk2

    When RE boots in disk1/2 the alternate disk is not used.

  2. Primary Disk, Upgrade Time: Thu Apr  1 20:47:54 IST 2021

    Primary disk: means the RE is booted from disk 1
    Upgrade Time: time of last vmhost version upgrade
  3.  set p and set b

    There are two sets of software boot images on the primary/secondary disk. We boot with one set, and when an upgrade is needed, it switches to use the other set. Similarly, on rollback, we switch to the other set. Two boot sets are present in every disk, 'set p' and 'set b'.

    Current root set: b --> indicates from which set the disk is booted, here it is set b.

    When a vmhost software upgrade is done, the new image is installed in the alternate set which is not the root set

    broot@jtac-mx2020-r2003-re0> request vmhost software add /var/tmp/junos-vmhost-install-mx-x86-64-16.1R6-S3.1.tgz no-validate reboot.


    The RE is booted with the boot image in set p

    user@mx-re0> show vmhost version 
    Current root details,           Device sda, Label: jrootp_P, Partition: sda3
    Current boot disk: Primary
    Current root set: p
    UEFI    Version: NGRE_v00.53.00.01

    Primary Disk, Upgrade Time: Fri May 14 12:55:52 IST 2021

    Version: set p
    VMHost Version: 3.1198
    VMHost Root: vmhost-x86_64-16.1R6-20171026_0422_builder
    VMHost Core: vmhost-core-x86_64-16.1R6-20171026_0422_builder
    kernel: 3.10.79-ovp-rt74-WR6.0.0.20_preempt-rt
    Junos Disk: junos-install-x86-64-16.1R6-S3.1

    Version: set b
    VMHost Version: 3.1465
    VMHost Root: vmhost-x86_64-17.3R3-S8-20200319_0024_builder
    VMHost Core: vmhost-core-x86_64-17.3R3-S11-20210118_2225_builder
    kernel: 3.10.100-ovp-rt110-WR6.0.0.31_preempt-rt
    Junos Disk: junos-install-mx-x86-64-17.3R3-S11.4

     

    When a rollback is done, then the RE boots up from the image from the alternate root set

    user@mx-re0> request vmhost software rollback 
    user@mx-re0> request vmhost reboot 
    Reboot the vmhost ? [yes,no] (no) yes 

    user@mx-re0> show vmhost version 
    Current root details,           Device sda, Label: jrootb_P, Partition: sda4
    Current boot disk: Primary
    Current root set: b
    UEFI    Version: NGRE_v00.53.00.01

    Primary Disk, Upgrade Time: Fri May 14 12:55:52 IST 2021

    Version: set p
    VMHost Version: 3.1198
    VMHost Root: vmhost-x86_64-16.1R6-20171026_0422_builder
    VMHost Core: vmhost-core-x86_64-16.1R6-20171026_0422_builder
    kernel: 3.10.79-ovp-rt74-WR6.0.0.20_preempt-rt
    Junos Disk: junos-install-x86-64-16.1R6-S3.1

    Version: set b
    VMHost Version: 3.1465
    VMHost Root: vmhost-x86_64-17.3R3-S8-20200319_0024_builder
    VMHost Core: vmhost-core-x86_64-17.3R3-S11-20210118_2225_builder
    kernel: 3.10.100-ovp-rt110-WR6.0.0.31_preempt-rt
    Junos Disk: junos-install-mx-x86-64-17.3R3-S11.4

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