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

  • Cisco Router Setup Guide and Tutorial Howto With Commands and Examples
  • Linux Bash Script To List All Connected IPs and their network name
  • Cisco Switches How To Get Of Port Line Status Console Messages
  • Cisco DHCP Snooping Relay Setup Information
  • Cisco Switch Setup Guide Command List
  • Cisco 2960 Switch Reset To Factory Defaults
  • How To Boot Cisco CUCM UCSInstall 8.6, 10, 11 and 12 on KVM/Proxmox
  • VBOX VirtualBox How To Import Raw .img Disk File
  • Windows Server 2012, 2016, 2019 How To Install and Missing Disabled Telnet Client
  • proxmox vm networking breaks when you restart your network on the hostnode
  • Linux ln symlink how to update existing symbolic link
  • Ubuntu 18.04 / Linux Mint 19.1 Cannot Type or Login - solution
  • LUKS Hard Drive Encryption on Linux Mint Ubuntu Debian etc how to mount encrypted hard drive
  • How to use nmap locate other machines/computers/servers on your network using nmap
  • Linux Mint 18.2 Create Config File To Start Application Upon Login
  • Dell Wyse Thin Client BIOS Access Key
  • sudoers file in /etc warning about comments/includes!
  • Centos 7 Reallocate logical volume space to another
  • lvm how to reduce volume size
  • letsencrypt certbot error "Unable to find a virtual host listening on port 80 which is currently needed for Certbot to prove to the CA that you control your domain. Please add a virtual host for port 80."