...

• BackingUp: When the backup process begins, the VM will transition from the Ready or Stopped to the BackingUp state, this state cannot be reached otherwise. During the backup process, the backup job will be queued alongside the other VM jobs; therefore, we will not have to worry about the VM being stopped/started during the backup, as each job is processed sequentially for each given VM.
• BackupError: If an exception which cannot be automatically recovered from happens (if the MGMT/agent service goes down, for example) or the job times out, the VM will go from the BackingUp to the BackupError state. While the VM is in this state, the VM may not be started, stopped, rebooted, migrated or snapshotted; its volumes cannot be attached, detached, migrated or snapshotted. An operator must read the logs and recover the VM manually from The finishBackupChain API may be called to try to fix this state.

The proposed VM backup creation workflow is summarized in the following diagram. Every step is repeated for all the volumes of the VM, except the virDomainSnapshotCreateXML step and the validation step, which are done for the VM as a whole.

...

To allow operators to pause the compression processes, the backup.compression.task.enabled account/domain/global setting will be created, when set to false in the global scope, no compression jobs will be executed, regardless of the value in other scopes. When true in the global scope, you may disable the compression task for certain domains or accounts by setting the value to false in the domain/account.

4.0.2 Ending the backup chain

The API finishBackupChain will be added to allow users to force a backup chain on a VM to end. This API may be called on VMs that are on the BackupError state and it will do a best-effort attempt at normalizing the VM and returning it to its original state, as well as finishing the backup chain on the VM. The API hast the following parameter:

4.1. Backup Restoration

As with the backup creation, this process will be queued with the other VM jobs and serialized, so we will not have to worry about the VM starting during the restoration process. Furthermore, the current backup chain will be severed.

...