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 use ifplugd in Linux to execute a command or script when a NIC cable is unplugged or plugged in
  • dd how to backup and restore disk images including compression with gzip
  • mpv / mplayer with Radeon / AMD GPU Video Card Driver enable VDPAU GPU Accelerated Video Decoding
  • Wordpress Reset Blog User Password from MySQL Using Linux Bash and not PHPMyadmin
  • Ubuntu Linux Mint Debian xorg performance and tear-free tuning for AMD Radeon Based Cards
  • Centos 7 Stopped and Disabled Firewalld and ports still blocked
  • MariaDB / MySQL Reset Root Forgotten Password on Centos 7
  • Centos 7 How to install Mysql/Mariadb
  • PHP 7.2, Apache and Centos 7 How To Install
  • Ubuntu Debian Linux Mint r8169 r8168 Network Driver Problem and Solution
  • Linux 3D Performance benchmarks with glxgears 59-60fps solution
  • How To Install Asterisk 16 17 on Debian Ubuntu Linux
  • Linux Ubuntu Debian Centos How To Make a Bootable Windows 7, 8, 10, 2016, 2019 Server USB from ISO
  • How To Restore Windows MBR Bootsector from Linux using syslinux
  • Linux Ubuntu Cannot Print Large Images
  • Cannot Print PDF Solution and Howto Resize
  • Linux Console Login Screen TTY Change Message
  • Apache Cannot Start Listening Already on 0.0.0.0
  • MySQL Bash Query to pipe input directly without using heredoc trick
  • CentOS 6 and 7 / RHEL Persistent DHCP Solution