Storage

Snapshots in Apache CloudStack can exist at two levels — VM snapshots and volume snapshots — each serving different purposes and stored in different locations. VM Snapshots A VM snapshot is a hypervisor-level checkpoint of an entire virtual machine. It captures the VM’s disk state and optionally its memory, allowing fast rollback to a previous state. Key points: Stored on primary storage. Created quickly without full data copy. Can include memory state for live restore....

When CloudStack deploys a VM from a template, it uses a linked clone instead of creating a full copy of the disk. This approach saves both time and storage space. What Is a Linked Clone A linked clone is a virtual disk that shares the same base image as another VM or template. It doesn’t duplicate the full data. Instead: The base disk (template) is read-only. The linked clone stores only changes (writes made by the VM)....

Primary storage in CloudStack holds the root volumes of running virtual machines and data volumes attached to them. It operates at the cluster level — all hosts within a cluster share access to the same primary storage pool. Local Storage Each hypervisor uses its own local disk for VM volumes. There is no shared storage between hosts. Characteristics No need for expensive centralized SAN/NAS. Limited functionality — no live migration or HA....