Configuring the processor for a DB instance class in RDS for Oracle

Amazon RDS DB instance classes support Intel Hyper-Threading Technology, which enables multiple threads to run concurrently on a single Intel Xeon CPU core. Each thread is represented as a virtual CPU (vCPU) on the DB instance. A DB instance has a default number of CPU cores, which varies according to DB instance class. For example, a db.m4.xlarge DB instance class has two CPU cores and two threads per core by default—four vCPUs in total.

Overview of processor configuration for RDS for Oracle

When you use RDS for Oracle, you can usually find a DB instance class that has a combination of memory and number of vCPUs to suit your workloads. However, you can also specify the following processor features to optimize your RDS for Oracle DB instance for specific workloads or business needs:

You can control the number of CPU cores and threads for each core separately. You can set one or both in a request. After a setting is associated with a DB instance, the setting persists until you change it.

The processor settings for a DB instance are associated with snapshots of the DB instance. When a snapshot is restored, its restored DB instance uses the processor feature settings used when the snapshot was taken.

If you modify the DB instance class for a DB instance with nondefault processor settings, either specify default processor settings or explicitly specify processor settings at modification. This requirement ensures that you are aware of the third-party licensing costs that might be incurred when you modify the DB instance.

There is no additional or reduced charge for specifying processor features on an RDS for Oracle DB instance. You're charged the same as for DB instances that are launched with default CPU configurations.

DB instance classes that support processor configuration

You can configure the number of CPU cores and threads per core only when the following conditions are met:

You can use the following AWS CLI command to show the default vCPUs, cores, threads per core, and valid numbers of cores for an instance class. Replace r7i.48xlarge in the sample command with the name of your instance class.

aws ec2 describe-instance-types \
    --instance-types r7i.48xlarge \
    --query '{
        DefaultVCPUs: InstanceTypes[0].VCpuInfo.DefaultVCpus,
        DefaultCores: InstanceTypes[0].VCpuInfo.DefaultCores,
        DefaultThreadsPerCore: InstanceTypes[0].VCpuInfo.DefaultThreadsPerCore,
        ValidCores: InstanceTypes[0].VCpuInfo.ValidCores
    }' \
    --output json

In the following table, you can find the DB instance classes that support setting a number of CPU cores and CPU threads per core. You can also find the default value and the valid values for the number of CPU cores and CPU threads per core for each DB instance class.