VMWare ESX Server – Virtual machine templates
Posted by decipherinfosys on June 5, 2009
Among the many best features of ESX server, virtual machine templates is one of the time saving features that system administrators can rely on to deploy servers at ease.
A template is a ‘pristine’ image of a server that can be used to create and provision new virtual servers on the fly in the ESX server environment. The template includes an operating system, its configuration and other set of applications installed on a typical server. There are four options related to templates in Virtual Center when you right click on a Virtual Machine or template that a system administrator needs to be aware of. Each option performs a different task and it is generally confusing to the new ESX server administrators. This post explains those options.
The options are as follows:
- Migrate – Selecting this option moves virtual machine from on ESX server host to another host. Without VMotion installed, this is a cold migration process that requires the virtual machine to be powered off before being migrated.
- Clone – It creates an exact copy of a virtual machine. Guest OS customization is required before powering on the cloned virtual machine in order to avoid SID and IP address conflicts in Windows operating system.
- Clone to Template – This option keeps the original virtual machine and creates a template.
- Convert to Template – This option converts the selected virtual machine to template and the original virtual machine disappears
Once a template is created, using Virtual Center it can be used in the following ways:
- Cloned to create a new template
- Converted to a virtual machine (The template disappears once the virtual machine is generated)
- Deploy virtual machine – This wizard driven option allows to keep the original template and offers guest OS customizations (using Sysprep) to create a new virtual machine
Few facts about templates:
• VMWare Virtual Center is needed to create a template. It cannot be created with a stand alone ESX server
• Never power-on a template
• Templates can be used to deploy virtual machines across different ESX servers hosts managed by the Virtual Center
There are a few interesting cloning options in VMWare provided by VMWare converter. We will discuss those in the next post.
- More information about VMWare templates and the best practices can be found in the following VMWare document: http://www.vmware.com/pdf/vc_2_templates_usage_best_practices_wp.pdf