Ubuntu Vm Images _top_ -

virt-customize -a ubuntu.qcow2 --install prometheus-node-exporter virt-customize -a ubuntu.qcow2 --ssh-inject ubuntu:file:/home/me/key.pub This tool mounts the filesystem offline – significantly faster than booting. Even a perfect image can perform badly if the hypervisor configuration mismatches. 6.1 Disk I/O: Writeback vs. None Libvirt’s default cache mode for QCOW2 is writeback . This is dangerous: host crash = data loss in guest. Change to writethrough or none (if using persistent memory). To check:

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: ubuntu vm images

<memoryBacking> <locked/> </memoryBacking> The serial console is your only lifeline. Common failures: virt-customize -a ubuntu

: Never dd a cloud image directly to a block device without resizing partitions. Always use qemu-img resize followed by a boot that runs growpart and resize2fs . And always, always keep a serial console log. None Libvirt’s default cache mode for QCOW2 is writeback