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11.6. Using Koan

Whether you are provisioning guests on a virtual machine or reinstalling a new distribution on a running system, koan works in conjunction with Cobbler to provision systems on the fly.

11.6.1. Using Koan to Provision Virtual Systems

If you have created a virtual machine profile as documented in Section 11.3, “Adding a Profile to Cobbler”, you can use koan to initiate the installation of a virtual guest on a system.
For example, say you've created a Cobbler profile such as the following: 
cobbler add profile --name=virtualfileserver --distro=rhel-i386-server-5 --virt-file-size=20 --virt-ram=1000
This profile is for a fileserver running Red Hat Enterprise Linux 5 with a 20GB guest image size and alloted 1GB of system RAM.
To find the name of the virtual guest system profile, run the following with koan: 
koan --server=hostname --list=profiles
This command lists all of the available profiles created with cobbler profile add.
Then, begin the process of creating the image file and starting the installation of the virtual guest system. 
koan --virt --server=cobbler-server.example.com --profile=virtualfileserver --virtname=marketingfileserver
The command specifies that a virtual guest system be created from the Cobbler server (hostname cobbler-server.example.com) using the virtualfileserver profile. The virtname option specifies a label for the virtual guest, which by default is labeled with the system's MAC address.
Once installation of the virtual guest is complete, it can be used as any other virtual guest system.

11.6.2. Using Koan to Re-install Running Systems

There may be instances where you need to re-install a machine with another operating system while it is still running. koan can help you by destructively replacing a running system with a new installation from the available Cobbler profiles.
To replace a running system and install a new one, run the following command on the system itself: 
koan --replace-self --server=hostname --profile=name
This command, when executed on the running system to be replaced, will start the provisioning process and replace its own system using the profile in --profile=name on the Cobbler server specified in --server=hostname.