KVM/QEMU Base/Template Images and the power they provide

 qemu-img create -b centos.5-8.x86.20120308.qcow2 -f qcow2 ../kvmguests/25000-centos5.8x86.qcow2
Formatting '../kvmguests/25000-centos5.8x86.qcow2', fmt=qcow2, backing_file=centos.5-8.x86.20120308.qcow2, size=10485760 kB

-b the source/base image

-f format is qcow2 and the location of the destination image

What is so special about this?  It's even quicker than creating a template with OpenVZ but this is an actual OS.

It saves time and disk space because it only writes the changes to the file of your image since the base OS/image is being used as a backing.  This means you could quickly and in an automated fashion create several servers for testing purposes for your applications or stress testing etc..

But there is one caveat and it's that you can't afford to lose the base image, it can't move or be modified/harmed otherwise the resulting images creating from it will stop working or have issues.  So it does introduce an unwanted and single point of failure, this is fine for testing but probably not wise to do for mission critical situations.


Tags:

kvm, qemu, template, images, img, centos, qcow, kvmguests, formatting, fmt, backing_file, kb, format, destination, quicker, creating, openvz, os, saves, disk, writes, backing, automated, servers, purposes, applications, etc, caveat, modified, harmed, resulting, unwanted,

Latest Articles

  • How to allow SSH root user access in Linux/Debian/Mint/RHEL/Ubuntu/CentOS
  • Ansible Tutorial - Playbook How To Install From Scratch and Deploy LAMP + Wordpress on Remote Server
  • Ceph Install Errors on Proxmox / How To Fix Solution
  • Proxmox Update Error https://enterprise.proxmox.com/debian/pve bullseye InRelease 401 Unauthorized [IP: 144.217.225.162 443]
  • QEMU/KVM How to Hot-add A Virtual Disk .raw/.qcow2 via QEMU Monitor Commands
  • Proxmox How To Enable Ceph Distributed Storage Cluster with OSD and Pools
  • pulseaudio issue on QEMU/KVM guest VM when microphone is replugged/unplugged pulseaudio: pa_threaded_mainloop_lock failed pulseaudio: Reason: Invalid argument
  • Ubuntu Linux Mint - Volume Control Stopped Working
  • Proxmox Services Won't Start Failed to start The Proxmox VE cluster filesystem. Proxmox VE firewall. PVE Status Daemon. Proxmox VE scheduler. PVE Cluster HA Resource Manager Daemon. PVE Local HA Resource Manager Daemon.
  • Proxmox Guide FAQ / Errors / Howto
  • Virtualbox Vbox Issue Cannot Enable Nested Virtualization Button is Grayed/Greyed Out and Unclickable HowTo Solution
  • Virtualbox VBOX Howto Port Forward To Guests
  • Linux Ubuntu Debian Centos Mint - How To Check if Intel VT-x or AMD-V Hardware Virtualization is Enabled?
  • Linux Howto Zip Multiple Files and Directories
  • Windows Cannot Format USB drive Device Media is Write Protected Error Solution
  • Linux Mint 20 cannot install snapd missing solution
  • Virtualbox VBOX How To Install Guest-Utils/GuestUtils so drag and drop and clipboard works Ubuntu Mint Debian Linux
  • How to install Kubernetes with microk8s and deploy apps on Debian/Mint/Ubuntu Linux
  • vi how to delete everything to the end of the line or the rest of the line from the cursor
  • Cisco Howto Configure Console Port/Terminal/Comm Server with Async Cable Setup