https://docs.databricks.com/security/keys/customer-managed-keys-storage-aws.html#introduction

The Databricks cluster’s EBS volumes (optional) - For Databricks Runtime cluster nodes and other compute resources in the Classic data plane, you can optionally use the key to encrypt the VM’s remote EBS volumes.

Note :

Serverless SQL warehouses do not use customer-managed keys for EBS storage encryption, which is an optional part of the customer-managed keys for workspace storage feature. Disks for serverless compute resources are short-lived and tied to the lifecycle of the serverless workload. For example, when serverless SQL warehouses are stopped or scaled down, the VMs and their storage are destroyed. See Serverless compute and customer-managed keys.