Compute Zone Extended CPU Configuration

OnApp provides a possibility to use the extended CPU configuration to group compute resources with similar CPU performance characteristics into compute zones. The extended CPU configuration allows to ensure consistent CPU performance within similar compute resources in the compute zone. The hot migration inside compute zones with the extended CPU configuration is more reliable. Moreover, you can set different prices in buckets for compute zones according to their CPU performance.

The extended CPU configuration is implemented on a per-compute-zone basis. The compute zone with the extended CPU configuration is automatically assigned to a CPU model with a set of default and additional CPU flags. The CPU model is selected based on the CPU characteristics common for all compute resources assigned to one compute zone. The default CPU flags are assigned to the zone automatically and you cannot edit them; the additional flags are optional and you can enable or disable them. In this document, you can find information on how to enable and manage the extended CPU configuration.

The extended CPU configuration is applicable only to KVM compute resources. For better performance, it is not recommended to create mixed KVM/Xen compute zones.


Enable Extended CPU Configuration



You can enable the extended CPU configuration functionality while creating or editing a compute zone. After this functionality is enabled for the compute zone, all compute resources in this zone are automatically attached to a CPU model with a default set of CPU flags that are common for all compute resources within this zone and that cannot be disabled. You can also select some additional CPU flags that are applicable to all compute resources in the compute zone.

To view and manage the list of CPU flags available for a compute zone, proceed to the following section. 


Manage Extended CPU Configuration



After the extended CPU configuration is enabled for a compute zone, you can view and manage CPU configuration of this zone as follows:

  1. Go to your Control Panel > AdminSettings menu and click the Compute Zones icon.
  2. Click a label of the required compute zone.
  3. Expand the Tools menu and click the Manage CPU Configuration button.
  4. On the screen that appears, you will see the following information on CPU configuration: 

    • The CPU Model Configuration box provides a label of a CPU model set for this compute zone, as well as the list of default CPU flags that are enabled for each compute resource in this zone. You cannot edit the list of default CPU flags. 

    • The Additional CPU Flags box includes the list of additional CPU flags available for each compute resource in this zone. Click a CPU flag to enable or disable it. The enabled CPU flags are displayed in green boxes and the disabled CPU flags are dimmed. You can also click the Select All and Deselect All buttons to manage additional flags. Any changes you make with additional flags are applied immediately.


  • If a compute zone is attached to a CPU model and then one of the compute resources of this zone goes to maintenance mode, the set of CPU flags can be different when it goes back online. For more information, refer to the Maintenance Mode for Xen/KVM Compute Resources section.
  • Be careful when adding new compute resources to a compute zone with extended CPU configuration. For more information, refer to the following section.

Adding New Compute Resources to Compute Zone with Extended CPU –°onfiguration 



There are several scenarios that can take effect when a new compute resource is added to a compute zone with extended CPU configuration:

  • If the new compute resource has the same CPU configurations as those resources that are already in a compute zone, the new compute resource inherits the CPU model and CPU flags set in this compute zone.

  • If the new compute resource has CPU with better performance characteristics than those resources that are already in a compute zone, the new compute resource inherits the CPU model and CPU flags set in this compute zone. The other flags will be disabled and listed in the Unmatching CPU Flags box at the AdminSettings > Compute Resources > compute resource label > Tools > Extended CPU Configuration page. 

  • If the new compute resource has CPU with worse performance characteristics than those resources that are already in a compute zone, the CPU model of the entire compute zone and all compute resources in this zone is automatically downgraded. The list of default and additional CPU flags will be updated in order to include only those flags that are common for each compute resource in the compute zone. 

    • If a compute resource with worse performance characteristics than other resources is removed from a compute zone, the CPU model of the entire compute zone and all compute resources in this zone is automatically upgraded. The list of default and additional CPU flags will be updated in order to include only those flags that are common for each compute resource in the compute zone. 
    • To achieve a CPU consistency between compute resources in a compute zone, assign the compute resource with worse or better CPU performance characteristics to the compute zone, where a CPU model would correspond to the actual CPU performance.
    • When you add a new compute resource to a compute zone with extended CPU configuration, wait for CPU flags to be updated after all the related transactions are finished.

Additional Considerations for Virtual Servers



There are some additional considerations that you should take into account while creating VSs on compute resources with the extended CPU configuration: 

  • When a new compute resource with worse CPU performance characteristics is added to a compute zone, as a result, the CPU model is downgraded and unmatching CPU flags are disabled for this zone and all the compute resources with better CPU, virtual servers that were earlier built in this zone on compute resources with a bigger set of flags will preserve all their flags. However, since such a VS has more flags than the compute zone and all the compute resources in this zone, it will not be possible to migrate this VS. 
  • The migration of virtual servers with a set of flags different from those available on the compute zone level will become available only after the reboot of VS or its shutdown and subsequent startup. After the boot, the VS configuration is updated to include the relevant set of CPU flags. Consequently, the migration of the rebooted virtual server will become available again.

    For more information on how to reboot a VS, refer to the Virtual Server Power Options document.