 |
|
Content Owner: Roman Macek | ||||
Summary
Yes, CloudInit and Glance support - NEW
Details
In RHV by default, virtual machines created from templates use thin provisioning.
In the context of templates, thin provisioning of vm means copy on write (aka linked clone or difference disk) rather than a growing file system that only takes up the storage space that it actually uses (usually referred to as thin provisioning). All virtual machines based on a given template share the same base image as the template and must remain on the same data domain as the template. Do NOT delete the template if you have created virtual machines in this way from it as the vm depend on the existence of the base image!
You can however specify to deploy the vm from template as clone - which means that a full copy of the vm will be deployed. When selecting to clone you can then select thin (sparse) or pre-allocated provisioning of the full clone. Deploying from template as clone results in independence from the base image but space savings associated with using copy on write approaches are lost.
Important: The image used to create templates for RHV must be generalized e.g. using the Sysprep tool (for Windows) or sys-unconfig (for Linux). This approach is similar to the deployment with e.g. SCVMM (different to VMware, where the generalization and customization of the vm is done on deployment, allowing for a quick, direct conversion of a template to a vm and vice versa). With RHV, changes to the template image require a deployment, applying changes/updates with subsequent generalization, then a conversion back into a template.
While not the same as a classic template, RHV 3.3 introduced support for cloud-init, which facilitates the provisioning of virtual machines by performing the initial setup of networking, SSH keys, timezones, user data injection, and more.
In RHV 3.5 support was added consume (use), export and share images with Glance. Glance image services include discovering, registering, and retrieving virtual machine images.
In the context of templates, thin provisioning of vm means copy on write (aka linked clone or difference disk) rather than a growing file system that only takes up the storage space that it actually uses (usually referred to as thin provisioning). All virtual machines based on a given template share the same base image as the template and must remain on the same data domain as the template. Do NOT delete the template if you have created virtual machines in this way from it as the vm depend on the existence of the base image!
You can however specify to deploy the vm from template as clone - which means that a full copy of the vm will be deployed. When selecting to clone you can then select thin (sparse) or pre-allocated provisioning of the full clone. Deploying from template as clone results in independence from the base image but space savings associated with using copy on write approaches are lost.
Important: The image used to create templates for RHV must be generalized e.g. using the Sysprep tool (for Windows) or sys-unconfig (for Linux). This approach is similar to the deployment with e.g. SCVMM (different to VMware, where the generalization and customization of the vm is done on deployment, allowing for a quick, direct conversion of a template to a vm and vice versa). With RHV, changes to the template image require a deployment, applying changes/updates with subsequent generalization, then a conversion back into a template.
While not the same as a classic template, RHV 3.3 introduced support for cloud-init, which facilitates the provisioning of virtual machines by performing the initial setup of networking, SSH keys, timezones, user data injection, and more.
In RHV 3.5 support was added consume (use), export and share images with Glance. Glance image services include discovering, registering, and retrieving virtual machine images.
