System won't boot after applying updates

SUMMARY

System won't boot after applying updates

ISSUE

Purpose
System updated the OS won't load.

Cause
The most likely cause is a new kernel and unitrends-drivers packages did not get installed properly.

Resolution

There are two primary symptoms that have been seen and three methods we can clear this issue without having to reimage the appliance:

Option A: The DPU fails to boot with “Error 15: unable to find file” or similar.

Option B: The DPU fails to boot with a kernel panic

Option C: Rescue current Installation from image media:

Repair: Complete repair by reinstall of kernel and related packages. 

The DPU fails to boot with “Error 15: unable to find file” or similar.

                This has been seen on DPU 2000 and 3000.  The reason is that the supplied grub.conf points to the kernel at /kernel-2.6.18…. and the initrd at /initrd-2.6.18…. when those are in the /boot directory.  This can be remedied as follows:

1.      Let the system try to boot, and fail.  Hit a key to continue once “Error 15” is seen.

2.      Hit “e” to edit the boot options.

3.      Select the kernel line and hit “e”, scroll back with the arrow keys and change

kernel /vmlinuz-2.6.18-….

        To

kernel /boot/vmlinuz-2.6.18-…

Then, hit enter to commit

4.       Select the initrd line and hit “e”, scroll back with the arrow keys and change

initrd /initrd-2.6.18-….

        To

Initrd /boot/initrd-2.6.18-…

Then, hit enter to commit

5.       Then “b” to boot

6.      Once booted, edit /boot/grub/grub.conf to have the same changes, and save that file.

The DPU fails to boot with a kernel panic

This has been seen on many newer (x86_64) platforms.  Multiple unitrends-config packages may have been installed as part of the update.  This can be remedied as follows:

1. During boot choose previous kernel at "Recovery OS" prompt:
2. This should allow normal boot then access to complete repair

Rescue current Installation from image media:

1. Create reimage media and set to boot from USB via How to reimage a Unitrends appliance
2. Boot from the RecoveryOS Factory Image DVD. 
3. Go to the option for 'Rescue Installed System'.
4. When the system starts to boot select boot with networking.
5. You will be prompted that the system will try to locate the installed system, select or 
6. The system should be found and mounted to /mnt/sysimage.
7. Type 'chroot /mnt/sysimage'. This makes the mounted disk the system root filesystem.
8. Type 'service sshd start'.  This will start the SSH daemon and will allow remote access via SSH to the system.

Complete repair by reinstall of kernel and related packages. 

1. Reinstall unitrends drivers packages:
   • • yum reinstall unitrends-drivers

2. List the installed kernels

   # rpm -qa | grep kernel | sort kernel-3.10.0-1160.42.2.el7.x86_64 <--OLD KERNEL kernel-3.10.0-1160.53.1.el7.x86_64 <--NEW INCOMPLETE KERNEL kernel-tools-3.10.0-1160.53.1.el7.x86_64 kernel-tools-libs-3.10.0-1160.53.1.el7.x86_64

3. Now the kernel needs to be reinstalled.
   (below examples are per the above output modify as needed choosing the 'newest' kernel)
   • • yum reinstall kernel-3.10.0-1160.53.1.el7.x86_64
4. You may have to remove it before you can reinstall it.  If this is the case run this:
   • • rpm -e --nodeps --justdb kernel-3.10.0-1160.53.1.el7.x86_64
     • yum install kernel-3.10.0-1160.53.1.el7.x86_64
5.  Reboot

If you are unsure of ANY of these steps please call Unitrends for assistance.