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

  • QEMU-KVM soundhw deprecated how to enable sound in QEMU 4.x series
  • Virtualbox Error Cannot register the hard disk because a hard disk with UUID already exists solution
  • kernel: [549267.368859] mate-terminal[7871]: segfault at 2000000101 ip 00007f5d0a9548f0 sp 00007fff7012c610 error 4 in libgobject-2.0.so.0.4800.2[7f5d0a920000+52000]
  • apcupsd how to setup and monitor APC UPS units
  • How To Password Reset, Recover, Bypass, Remove and Unlock on Windows 10,8,7,Vista,XP,NT,2000,2003,2008,2012,2016,2019 Administrative Login Programs
  • Nvidia Ubuntu Linux Screentearing Video with solution driver
  • ?? Question Marks for time, permissions and size of a file?
  • mdadm how to stop a check
  • access denied by acl file qemu-kvm: bridge helper failed
  • Linux NIC connecting at 100M instead of 1000M gigabit speeds? It could be overheating
  • "This kernel requires the following features not present on the CPU: cmov Unable to boot - please use a kernel appropriate for your CPU.
  • http://vault.centos.org/5.9/os/i386/repodata/filelists.xml.gz: [Errno -1] Metadata file does not match checksum solution
  • Linux Ubuntu Wifi Disabled Only Works When Laptop Plugged Into Wall AC Power
  • CentOS 6 impossible to compile a newer libguestfs
  • chroot
  • How To Get Started on Ubuntu with gpt-2 OpenAI Text Prediction
  • Remove cloud-init in your VM
  • QEMU-KVM KVM Command Line Practical Guide
  • Linux How To Change NIC Name to eth0 instead of enps33 or enp0s25
  • virt-resize: error: libguestfs error: could not create appliance through libvirt.