{{tag>kvm image disck qcow2}}
Apply for: debian, linux...

====== Creating images ======

===== Creating base image: like creating normal image =====
    qemu-img create -f qcow2 windows-master.qcow2 10G

Install OS on that image.

    qemu-system-x86_64  -hda  windows-master.qcow2  -m  512  -boot d  -cdrom /home/user/isos/en_winxp_pro_with_sp2.iso

==== Debian ====
  * Use guilded lvm separate all
  * configure lvm manager and edit lv partitions
===== Creating working images =====

    qemu-img create -b windows-master.qcow2 -f  qcow2   windows-clone.qcow2
    
This working image have the same virtual size as the base image. The actual size is small because the working image only contain the difference to the base image from the time it is created.

* Important *: Never boot or modify the base image. It will cause inconsistency. working image = base image + (concat) diff.

    qemu-img info windows-clone.qcow2

    image: windows-clone.qcow2
    file format: qcow2
    virtual size: 10G (10737418240 bytes)
    disk size: 56K
    cluster_size: 4096
    backing file: windows-master.qcow2 (actual path: windows-master.qcow2)

Multiple working images can share the same base image.

==== Network ====

===== Rebasing: =====
Merging working image with based image to create a new indipendent base image.

    qemu-img convert windows-clone.qcow2 –O qcow2 windows-marketing.qcow2

* This need more study * Create cow new image with convert.

===== When there is a need to change base image to other location. =====

    qemu-img convert -O qcow2 -B master-windows2003-base.qcow2 master-windows2003.qcow2 final.qcow2
    
    
===== - cloud-init user login =====

==== - virt-customize ====

    $ virt-customize -a bionic-server-cloudimg-amd64.img --root-password password:coolpass

  * http://serverascode.com/2018/06/26/using-cloud-images.html

==== - cloud init image ====
<code>
$ ssh-keygen -f atomic_rsa
Generating public/private rsa key pair.
<truncating output>
$ cat atomic_rsa.pub 

$ vim meta-data

instance-id: Atomic01
local-hostname: atomic-host-001

$ vim user-data

#cloud-config
password: redhat
chpasswd: { expire: False }
ssh_pwauth: True
ssh_authorized_keys:
   - ... ssh-rsa new public key here user@host ...
</code>

    $ genisoimage -output atomic01-cidata.iso -volid cidata -joliet -rock user-data meta-data

====== Managing VMs ======
===== virtmanager =====
spice already supported from Fed 15.

    yum install kvm
    yum install virt-manager libvirt libvirt-python python-virtinst 


===== vm manger script =====

    yum install spice-client

Check enable_nat.sh for correct ethernet name (em1 vs eth0)
==== Configure Start scritp ====
The VM will be configured with ip, MAC, bridge in NAT mode...

Edit the followings:
  * IP
  * VNC
  * SPice
  * MAC
  * Hostname
  * 
===== Configure VMs =====
==== network, hostname, ip ====
Open VNC connection

Login with root:r4o9o9t5

user dev:dev

=== IP ===
Debian

http://www.linux-kvm.org/page/Networking

== Static IP ==
       auto eth0
       iface eth0 inet static
        address 192.168.0.7
        netmask 255.255.255.0
        gateway 192.168.0.254

Then restart network

    /etc/init.d/networking restart
    or
    ifdown ethx
    ifup ethx
    
=== apt-get ===

Now that Lenny has been archived, you will need to update your /etc/apt/sources.list file. It should now look like this:

    deb http://archive.debian.org/debian lenny main
    deb http://archive.debian.org/debian-security lenny/updates main
    deb http://archive.debian.org/debian-volatile lenny/volatile main
    deb http://archive.debian.org/backports.org lenny-backports main

=== tcp_window_scaling ===

*Attention*

Causes problem when debian guests download large file from internet. Disable tcp_window_scaling on host machine.

    net.ipv4.tcp_window_scaling=0"
    sysctl -w net.ipv4.tcp_window_scaling=0