Skip to main content

Flavor Restrictions

Flavors in our system come with certain restrictions based on specific labels assigned to them. These labels determine the capabilities, limitations, and suitability of flavors for different use cases. Understanding these restrictions is essential when selecting the appropriate flavor for your needs.

Current Labels​

  • no-snapshot: Flavors with this label do not support the creation of snapshots. This means you cannot capture the current state of the virtual machine for backup or cloning purposes. Choose flavors without this label if snapshot functionality is required for your workload.

  • no-hibernation: Flavors marked with this label do not support hibernation. Hibernation allows you to save the state of a virtual machine to disk and power it off, conserving resources. If you need to use hibernation, select a flavor that does not have the no-hibernation label.

  • local-storage-only: Flavors with this label are restricted to using local hypervisor storage for the boot process. These flavors cannot boot from Ceph or other shared storage systems. However, attaching non-bootable volumes to the VM after deployment is still supported.

Understanding Flavor Labels​

Labels are used to communicate specific capabilities or limitations of a flavor:

  • no-snapshot: Indicates that snapshot operations are disabled for this flavor. This might be due to technical limitations or performance considerations.

  • no-hibernation: Indicates that hibernation is not supported. This could be because the underlying hardware or virtualization technology does not support saving and restoring VM states for these flavors.

  • local-storage-only: Ensures that VMs launched with these flavors can only boot using local hypervisor storage. This restriction exists to maintain performance or compatibility with certain workloads. A detailed explanation will be displayed to users attempting unsupported operations.

Implications of the Labels​

No Snapshot​

  • Backup Limitations: Without snapshot support, you cannot create point-in-time backups of your virtual machine. Consider implementing alternative backup strategies, such as application-level backups or external data replication.

  • Cloning Restrictions: Snapshots are often used as a baseline for cloning virtual machines. Flavors with no-snapshot cannot be cloned using snapshot-based methods.

No Hibernation​

  • Resource Consumption: Without hibernation, virtual machines must be either running or completely shut down. You cannot save the machine state and reduce resource usage temporarily.

  • Startup Time: Hibernation allows for faster startup times since the VM resumes from a saved state. Without it, VMs must boot from scratch after being powered off.

Local Storage Only​

  • Boot Restrictions: VMs with this label cannot boot from shared storage like Ceph. They must use local hypervisor storage for the boot process.

  • Volume Attachment: Non-bootable volumes can still be attached to the VM after deployment.

  • Error Handling: If a user attempts to boot from a volume with a flavor labeled local-storage-only, an error message will be displayed stating: "Boot from Volume Not Possible for this flavor."

  • UI Messaging: The Deploy VM page will display a message: "The flavor type doesn’t allow boot from volume. Learn More" with a link to additional documentation explaining the restriction.

  • Live Documentation: A dynamic document will list all flavors restricted to local storage for easy reference.