KVM Panorama does not boot after adding a new virtual disk

• Panorama KVM does not boot after adding a new virtual disk
• Removing the new disk fixes the issue
• You can see similar output from the Serial Console

[    3.163480] md: Waiting for all devices to be available before autodetect
[    3.169687] md: If you don't use raid, use raid=noautodetect
[    3.175581] md: Autodetecting RAID arrays.
[    3.181971] md: autorun ...
[    3.185322] md: ... autorun DONE.
[    3.189356] Using alternate root: /dev/vda3...
[    3.194142] Using alternate root: /dev/xvda3...
[    3.198842] Using alternate root: /dev/nvme0n1p3...
[    3.204050] VFS: Cannot open root device "nvme0n1p3" or unknown-block(0,0): error -6
[    3.213374] Please append a correct "root=" boot option; here are the available partitions:

[...]

[    3.342901] Kernel Offset: 0x30400000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff)
[    3.346644] ---[ end Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0) ]---

• Panorama
• KVM

• The newly added disk got the priority order over the older system disk.
• The old system disk is not detected with the letter A (as the first disk)

The configuration of the old system disk must be fixed in order to always be the first disk.

• its letter must be A
• it must be the first in the order

1. Turn off the Panorama KVM
2. Remove the new disk from the Panorama KVM and keep only the old disks.
3. Open the KVM XML configuration of Panorama

admin@KVM-Server$ sudo virsh edit <Panorama>

4. Change the disk order in the XML configuration:

1. Identify the section of the configuration of the currently used old 81 GB system disk. 
   The section starts with <disk ...> and ends with </disk>. For instance:

EXAMPLE 1 -> NOT OK

    <disk type='file' device='disk'>
      <driver name='qemu' type='qcow2' discard='unmap'/>
      <source file='/var/lib/libvirt/images/Panorama-Disk01-old.qcow2'/>
      <target dev='vdb' bus='virtio'/>
      <address type='pci' domain='0x0000' bus='0x08' slot='0x00' function='0x0'/>
    </disk>

EXAMPLE 2 -> NOT OK

    <disk type='file' device='disk'>
      <driver name='qemu' type='qcow2'/>
      <source file='/home/user1/Desktop/Panorama-KVM-11.1.6-h4.qcow2' index='2'/>
      <backingStore/>
      <target dev='sda' bus='sata'/>
      <alias name='sata0-0-1'/>
      <address type='drive' controller='0' bus='0' target='0' unit='1'/>
    </disk>

2. Change the device letter, in order to be the letter a (i.e. from vdb to vda, from sdc to sda).
3. Also, change the actual disk order: 

• • In the example 1, the bus number makes the order
• Change the bus from 0x08 to 0x04 in order to make it the first disk available.

EXAMPLE 1 -> FIXED OK

    <disk type='file' device='disk'>
      <driver name='qemu' type='qcow2' discard='unmap'/>
      <source file='/var/lib/libvirt/images/Panorama-Disk01-old.qcow2'/>
      <target dev='vda' bus='virtio'/>
      <address type='pci' domain='0x0000' bus='0x04' slot='0x00' function='0x0'/>
    </disk>

• • In the example 2, the unit number makes the order
• Change the unit number from 1 to 0 in order to make it the first disk available.

EXAMPLE 2 -> FIXED OK

    <disk type='file' device='disk'>
      <driver name='qemu' type='qcow2'/>
      <source file='/home/user1/Desktop/Panorama-KVM-11.1.4-h7.qcow2' index='2'/>
      <backingStore/>
      <target dev='sda' bus='sata'/>
      <alias name='sata0-0-1'/>
      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
    </disk>

5. Save the configuration and reload the Panorama KVM settings.
6. Then, the next new disk should come further in the disks' order

Increasing the system disk from 81 to 224 GB is possible starting Panorama 11.1.5.

How to increase the system disk space on Panorama KVM