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Sysadmin Grub Help?

Discussion in 'System Administration' started by Jimmy, Sep 15, 2017.

  1. Jimmy

    Jimmy Well-Known Member

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    My local dev server upgraded fine. Just my OVH server is have an issue.
     
  2. eva2000

    eva2000 Administrator Staff Member

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    does the server us NVMe raid or something ? or Xeon D Broadwell based ?

    what about reverting to previous kernel
    Code (Text):
    grub2-set-default 1
    grub2-mkconfig -o /boot/grub2/grub.cfg
    reboot
    
     
  3. Jimmy

    Jimmy Well-Known Member

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    Yea, the server is using NVMe. But I have no issue booting from the grub prompt.
     
  4. eva2000

    eva2000 Administrator Staff Member

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    output for
    Code (Text):
    cat /etc/default/grub
    

    did using previous kernel suggestion work ?
     
  5. Jimmy

    Jimmy Well-Known Member

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    Reverted to previous kernel. Doesn't work. Still grub command prompt.
     
  6. Jimmy

    Jimmy Well-Known Member

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    Previous kernel didn't work.

    Sorry, had to wait to reboot. Below is the output.

    Code:
    # cat /etc/default/grub
    GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)"
    GRUB_DEFAULT=0
    GRUB_DISABLE_SUBMENU=true
    GRUB_TERMINAL_OUTPUT="console"
    GRUB_CMDLINE_LINUX="crashkernel=auto rhgb quiet rd.md.uuid=a032e06f:8e62819e:a4d2adc2:26fd5302"
    GRUB_DISABLE_RECOVERY="true"
    #GRUB_HIDDEN_TIMEOUT=0
    GRUB_TIMEOUT=2
    GRUB_DISABLE_LINUX_UUID=true
     
  7. eva2000

    eva2000 Administrator Staff Member

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    and output for
    Code (Text):
    df -hT
    

    Code (Text):
    grubby --info=ALL
    
     
  8. Jimmy

    Jimmy Well-Known Member

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    Code:
    # df -hT
    Filesystem     Type      Size  Used Avail Use% Mounted on
    /dev/md2       xfs       1.1T   42G  1.1T   4% /
    devtmpfs       devtmpfs   63G     0   63G   0% /dev
    tmpfs          tmpfs      63G     0   63G   0% /dev/shm
    tmpfs          tmpfs      63G  8.8M   63G   1% /run
    tmpfs          tmpfs      63G     0   63G   0% /sys/fs/cgroup
    /dev/nvme0n1p1 vfat      510M  3.5M  507M   1% /boot/efi
    tmpfs          tmpfs      13G     0   13G   0% /run/user/0
    
    Code:
    # grubby --info=ALL
    index=0
    kernel=/boot/vmlinuz-3.10.0-693.2.2.el7.x86_64
    args="ro crashkernel=auto rhgb quiet rd.md.uuid=a032e06f:8e62819e:a4d2adc2:26fd5302 "
    root=/dev/md2
    initrd=/boot/initramfs-3.10.0-693.2.2.el7.x86_64.img
    title=CentOS Linux (3.10.0-693.2.2.el7.x86_64) 7 (Core)
    index=1
    kernel=/boot/vmlinuz-3.10.0-514.26.2.el7.x86_64
    args="ro crashkernel=auto rhgb quiet rd.md.uuid=a032e06f:8e62819e:a4d2adc2:26fd5302 "
    root=/dev/md2
    initrd=/boot/initramfs-3.10.0-514.26.2.el7.x86_64.img
    title=CentOS Linux (3.10.0-514.26.2.el7.x86_64) 7 (Core)
    index=2
    kernel=/boot/vmlinuz-3.10.0-514.26.1.el7.x86_64
    args="ro crashkernel=auto rhgb quiet rd.md.uuid=a032e06f:8e62819e:a4d2adc2:26fd5302 "
    root=/dev/md2
    initrd=/boot/initramfs-3.10.0-514.26.1.el7.x86_64.img
    title=CentOS Linux (3.10.0-514.26.1.el7.x86_64) 7 (Core)
    index=3
    kernel=/boot/vmlinuz-3.10.0-514.21.2.el7.x86_64
    args="ro crashkernel=auto rhgb quiet rd.md.uuid=a032e06f:8e62819e:a4d2adc2:26fd5302 "
    root=/dev/md2
    initrd=/boot/initramfs-3.10.0-514.21.2.el7.x86_64.img
    title=CentOS Linux (3.10.0-514.21.2.el7.x86_64) 7 (Core)
    index=4
    kernel=/boot/vmlinuz-3.10.0-514.21.1.el7.x86_64
    args="ro crashkernel=auto rhgb quiet rd.md.uuid=a032e06f:8e62819e:a4d2adc2:26fd5302 "
    root=/dev/md2
    initrd=/boot/initramfs-3.10.0-514.21.1.el7.x86_64.img
    title=CentOS Linux (3.10.0-514.21.1.el7.x86_64) 7 (Core)
    index=5
    kernel=/boot/vmlinuz-0-rescue-1e98a4cc1263468b9f9a12e365316b95
    args="ro crashkernel=auto rhgb quiet rd.md.uuid=a032e06f:8e62819e:a4d2adc2:26fd5302 "
    root=/dev/md2
    initrd=/boot/initramfs-0-rescue-1e98a4cc1263468b9f9a12e365316b95.img
    title=CentOS Linux (0-rescue-1e98a4cc1263468b9f9a12e365316b95) 7 (Core)
    index=6
    non linux entry
    
     
  9. eva2000

    eva2000 Administrator Staff Member

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    Never used NVMe system before but i think it's because you mounted /boot outside of root directory at /

    CentOS 7 can be picky about having /boot, /var, /usr outside of root / partition CentOS 7.x - Tip: CentOS 7 DO NOT have /usr on separate partition

    my OVH server with CentOS 7
    Code (Text):
    df -hT
    Filesystem     Type      Size  Used Avail Use% Mounted on
    /dev/md1       ext4       69G   42G   24G  65% /
    devtmpfs       devtmpfs   16G     0   16G   0% /dev
    tmpfs          tmpfs      16G     0   16G   0% /dev/shm
    tmpfs          tmpfs      16G  8.6M   16G   1% /run
    tmpfs          tmpfs      16G     0   16G   0% /sys/fs/cgroup
    tmpfs          tmpfs      16G     0   16G   0% /tmp
    /dev/md2       ext4      151G  9.4G  134G   7% /home
    tmpfs          tmpfs     3.2G     0  3.2G   0% /run/user/0
    
     
  10. eva2000

    eva2000 Administrator Staff Member

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    might need to get OVH tech support involved could be something specific to NVMe drives ?

    dig though your boot logs
    Code (Text):
    journalctl -b --no-pager
    


    you'd be on your own for this.. beyond Centmin Mod type support
     
    • Informative Informative x 1
  11. eva2000

    eva2000 Administrator Staff Member

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  12. Jimmy

    Jimmy Well-Known Member

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    Put in a support ticket with OVH. Maybe they can solve the issue.

    I might get another server and setup the HD differently.
     
  13. pamamolf

    pamamolf Premium Member Premium Member

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    Ignore that post as the instructions will not help...

    I edit it and delete the instructions.
     
    Last edited: Sep 15, 2017
  14. Jimmy

    Jimmy Well-Known Member

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    @eva2000 Looking around in my /etc/ folder I see that the grub2-efi.cfg symlink is broken. My testing server that symlink is fine. Wanted to .bak that file and create a new symlink. Question: if I mess this up will my system not be able to boot? Don't want to do anything that will prohibit me from getting into the system from the grub command prompt. Or do you think this file has nothing to do with the issue.
     
  15. Jimmy

    Jimmy Well-Known Member

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  16. Jimmy

    Jimmy Well-Known Member

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    Solution:
    Code:
    yum reinstall grub2-efi shim
    Code:
    grub2-mkconfig -o /boot/efi/EFI/centos/grub.cfg
    The /boot/efi/EFI/centos/ folder lacked the grub.cfg file.
     
    • Informative Informative x 3
  17. eva2000

    eva2000 Administrator Staff Member

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    nice find so it's a UEFI boot thing !
     
  18. Jimmy

    Jimmy Well-Known Member

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    Found a couple threads about not booting and EFI and then compared my local server which is working and EFI to the online server. Not sure if I really needed to reinstall, but figured why not. Glad got this figured out.

    Thanks for all your help!
     
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  19. pamamolf

    pamamolf Premium Member Premium Member

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    Is there any command to know if the system is using UEFI or not?
     
  20. eva2000

    eva2000 Administrator Staff Member

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    seems it's at HowTos/Grub2 - CentOS Wiki

    and 25.5. Customizing the GRUB 2 Configuration File

    they all had df -hT mount for NVMe at /boot/efi ?
    Code (Text):
    /dev/nvme0n1p1 vfat      510M  3.5M  507M   1% /boot/efi