Red Hat Summit8.2. Heterogeneous cluster support
A heterogeneous cluster is a cluster where nodes have differing architectures. Heterogeneous clusters promote optimal compute resource usage by mixing different types of hardware in one cluster.
Golden image support for heterogeneous clusters is a Technology Preview feature only. Technology Preview features are not supported with Red Hat production service level agreements (SLAs) and might not be functionally complete. Red Hat does not recommend using them in production. These features provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process.
For more information about the support scope of Red Hat Technology Preview features, see Technology Preview Features Support Scope.
With heterogenous clusters, you can match workloads to hardware intended for the workload task instead of general purpose compute platforms. For example, GPU and general purpose compute resources could be combined and workloads assigned to the appropriate hardware.
If golden image support is disabled in a heterogeneous cluster, you can encounter inconsistencies between node and image architectures. This happens when images are used for virtual machine creation that do not match the node architecture. This can lead to the failure of virtual machine boot up or virtual machines that do not run as expected. The warning level alert HCOMultiArchGoldenImagesDisabled is produced when this feature is not enabled in a heterogeneous cluster.
If you have a heterogeneous cluster but do not want to enable multiple architecture support, you can modify the workloads node placement in the HyperConverged custom resource (CR) to include only nodes with a specific architecture.
Golden image support for heterogeneous clusters extends golden image support in the following areas:
- Enables VM creators to deploy persistent virtual machines with specific architectures.
- Enables VM creators to define custom golden images that support heterogenous clusters.
The same golden image can be used with nodes of different architectures if the boot image supports the required architectures. For example, a golden image that supports both ARM and AMD architectures can be used with both types of nodes.
Golden image support for heterogeneous clusters is not enabled by default. You can enable heterogenous cluster support by setting the feature gate in the HyperConverged CR.
8.2.1. Enabling heterogeneous cluster support
You can enable golden image support for heterogeneous clusters by setting the enableMultiArchBootImageImport feature gate to true in the HyperConverged custom resource (CR).
Golden image support for heterogeneous clusters is a Technology Preview feature only. Technology Preview features are not supported with Red Hat production service level agreements (SLAs) and might not be functionally complete. Red Hat does not recommend using them in production. These features provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process.
For more information about the support scope of Red Hat Technology Preview features, see Technology Preview Features Support Scope.
Prerequisites
-
You have access to the cluster as a user with
cluster-adminpermissions. -
You have installed the OpenShift CLI (
oc).
Procedure
Enable the
enableMultiArchBootImageImportfeature gate by running the following command:$ oc patch hyperconverged kubevirt-hyperconverged -n openshift-cnv \ --type json -p '[{"op":"replace","path":"/spec/featureGates/enableMultiArchBootImageImport", "value": true}]'
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