An instance is a copy of the selected disks of a VM made at a given time and stored as a VM template. In private cloud with hypervisors, the platform saves the disks and a copy of the original template definition, unless the VM was captured from outside Abiquo, in which case it saves the configuration of the VM. The platform stores the instance under the master template in the Apps library. In public cloud providers, the platform saves the instance as a new VM template with disks and the configuration of the VM. Remember to enter a name that will help you to identify the instance template.
In the platform, hard disks are non-persistent and they are destroyed when deleted from the VMs or when the VMs are undeployed. In private cloud datacenters with hypervisors, the platform creates hard disks on the hypervisor datastore.
In private cloud datacenters, volumes are persistent and independent of the VMs. The platform creates volumes on external storage devices. Volumes are available in private cloud datacenters with hypervisors and they require the external storage feature.
A persistent VM template has one or more persistent disks on external storage volumes. Persistent VM templates are available in private cloud datacenters with hypervisors and they require the external storage feature.
Persistent VM template disks are associated with a specific virtual datacenter. Hypervisors running persistent VMs will work directly from any persistent volumes. VM data stored on a persistent disk will be persisted on the external storage device. When you undeploy a VM, all changes made to the non-persistent disks will be lost. The next time you deploy the VM, the non-persistent template files will be freshly created, for example, standard template disks will be copied again from the appliance library to the target hypervisor. Note that it is not necessary for you to use a persistent disk as a system disk when you create a persistent VM.