cloudstack/docs/en-US/update-iso-vm.xml

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XML

<?xml version='1.0' encoding='utf-8' ?>
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<section id="update-iso-vm">
<!-- CLOUDSTACK-667 -->
<title>Changing a VM's Base Image</title>
<para>Every VM is created from a base image, which is a template or ISO which has been
created and stored in &PRODUCT;. Both cloud administrators and end users can create and
modify templates, ISOs, and VMs.</para>
<para>In &PRODUCT;, you can change an
existing VM's base image. For example, suppose there is a template based
on a particular operating system, and the OS vendor releases a software patch. The
administrator or user naturally wants to apply the patch and then make sure existing VMs
start using it. Whether a software update is involved or not, it's also possible to simply
switch a VM from its current template to any other desired template.</para>
<para>To change a VM's base image, call the restoreVirtualMachine API command and pass in the virtual machine
ID and a new template ID. The template ID parameter may refer to either a template or an
ISO. When this call occurs, the VM's root disk is first destroyed, then a new root disk is
created from the source designated in the template ID parameter. The new root disk is
attached to the VM, and now the VM is based on the new template.</para>
</section>