<memoryBacking> <locked/> </memoryBacking> The serial console is your only lifeline. Common failures:
| Format | Primary Use Case | Key Characteristics | |--------|------------------|----------------------| | ( .qcow2 ) | OpenStack, KVM, Proxmox | No graphical installer; uses cloud-init ; minimal package set; optimized for first-boot configuration | | Cloud Images ( .img ) | AWS, GCP, Azure (after conversion) | Raw format with partition table; requires cloud-specific agents (e.g., waagent for Azure) | | Vagrant Boxes ( box file) | Development (VirtualBox, libvirt) | Includes VirtualBox Guest Additions or virtio drivers; user vagrant with insecure key; shared folder support | | OVA/OVF | vSphere, ESXi | VMX descriptor + VMDK disk; typically pre-configured for VMware paravirtual SCSI and vmxnet3 | | Live Server ISO | Manual interactive install | Contains debian-installer or Subiquity; not a VM image per se but can generate one post-install | ubuntu vm images
virsh dumpxml vm-name | grep "driver name" # Look for cache='none' or cache='writethrough' Ubuntu’s kernel sees vCPUs as separate cores. For NUMA-aware workloads (databases), pin vCPUs to physical cores: Generate a fake metadata disk: cloud-localds seed
Packer launches a VM, runs an autoinstall (Ubuntu's new declarative installer), provisions with shell/Ansible, and outputs QCOW2, VMDK, or raw. Generate a fake metadata disk: Proxmox | No graphical installer
cloud-localds seed.iso user-data meta-data # Attach seed.iso as a CDROM to the VM This allows testing cloud-init behavior without a real metadata service. For quick fixes without booting the VM: