# Optimize CPUs for RDS for SQL Server license-included instances
With RDS for SQL Server, you can use Optimize CPU by specifying processor features to configure the vCPU count on your DB instance while maintaining the same memory and IOPS. You can achieve desired memory-to-CPU ratios for specific database workload requirements and reduce licensing costs for Microsoft Windows OS and SQL Server, which are based on vCPU count.
To specify processor feature, use the following parameters:
```
--processor-features "Name=coreCount,Value=value" \
"Name=threadsPerCore,Value=value"
```
+ **coreCount** – Specify the number of CPU cores for the DB instance, to optimize licensing costs for DB instances. See [DB instance classes that support Optimize CPUDB instance class support](SQLServer.Concepts.General.OptimizeCPU.Support.md) to find the allowed values for core count for a selected instance type.
+ **threadsPerCore** – Specify the threads per core to define the number of threads per CPU core. See [DB instance classes that support Optimize CPUDB instance class support](SQLServer.Concepts.General.OptimizeCPU.Support.md) to find the allowed values for threads per core for a selected instance type.
Sample command to create an RDS for SQL Server instance with Optimize CPU settings:
```
aws rds create-db-instance \
--engine sqlserver-ee \
--engine-version 16.00 \
--license-model license-included \
--allocated-storage 300 \
--master-username myuser \
--master-user-password xxxxx \
--no-multi-az \
--vpc-security-group-ids myvpcsecuritygroup \
--db-subnet-group-name mydbsubnetgroup \
--db-instance-identifier my-rds-instance \
--db-instance-class db.m7i.8xlarge \
--processor-features "Name=coreCount,Value=8" "Name=threadsPerCore,Value=1"
```
In this example, you create a `db.m7i.8xlarge` instance, which by default has a coreCount of 16. By using Optimize CPU, you opt for a coreCount of 8, resulting in an effective vCPU count of 8.
If you create the instance without the `--processor-features` parameter, core count is set to 16 and threads per core is set to 1 by default, resulting in a default vCPU count of 16.
Some considerations to keep in mind while specifying processor features:
+ **Create** – Specify both the `coreCount` and `threadsPerCore` for the `processor-features` parameter from the allowed values. See [DB instance classes that support Optimize CPUDB instance class support](SQLServer.Concepts.General.OptimizeCPU.Support.md).
+ **Modify** – When modifying from one instance class configured with Optimize CPU settings to another one that supports Optimize CPU settings, you must specify the default processor settings using the `--use-default-processor-features` parameter or explicitly define the options during the modify request.
**Note**
Changing the vCPU count can have implications for the licensing fee cost associated with the DB instance.
+ **Snapshot restore** – When restoring a snapshot to the same instance type as source, the restored DB instance inherits the Optimize CPU settings from the snapshot. If restoring to a different instance type, you need to define the Optimize CPU settings for the target instance or specify the `--use-default-processor-features` parameter.
+ **Point-in-time restore** – Point-in-time restore (PITR) involves restoring a specific snapshot based on the designated time for PITR and subsequently applying all transactional log backups to that snapshot, thereby bringing the instance to the specified point in time. For PITR, the Optimize CPU settings, `coreCount` and `threadsPerCore`, are derived from the source snapshot (not the point in time) unless custom values are specified during the PITR request. If the source snapshot being used is enabled with Optimize CPU settings and you are using a different instance type for PITR, you must define the Optimize CPU settings for the target instance or specify the `—-use-default-processor-features` parameter.
## Limitations
The following limitations apply when using Optimize CPU:
+ Optimize CPU is supported with Enterprise, Standard, and Web Editions only.
+ Optimize CPU is available on select instances. See [DB instance classes that support Optimize CPUDB instance class support](SQLServer.Concepts.General.OptimizeCPU.Support.md).
+ Customizing the number of CPU cores is supported on instance sizes of `2xlarge` and above. With these instance types, the minimum number of vCPCU supported for Optimize CPU is 4.
+ Optimize CPU allows only 1 thread per core since Hyper-Threading is disabled for instances starting from 7th generation that support Optimize CPU.
# DB instance classes that support Optimize CPU
RDS for SQL Server supports Optimize CPU beginning with the 7th Generation instance class type. Additionally, RDS provides a detailed billing breakdown of RDS DB instance and third-party licensing fees, starting from the 7th Generation instance class type, regardless of whether the Optimize CPU feature is enabled.
RDS for SQL Server provides support for Optimize CPU on specific instance sizes, with the smallest instance size supported being `2xlarge`. The minimum configuration supported is 4 vCPUs. The table below outlines the DB instance classes that support the Optimize CPU, including their default and valid values for CPU cores, CPU threads per core and vCPUs:
**General purpose instances**
| Instance type | Default vCPUs | Default CPU cores | Valid CPU cores | Valid threads per core |
| --- | --- | --- | --- | --- |
| `m7i.large` | 2 | 1 | 1 | 2 |
| `m7i.xlarge` | 4 | 2 | 2 | 2 |
| `m7i.2xlarge` | 4 | 4 | 1,2,3,4 | 1 |
| `m7i.4xlarge` | 8 | 8 | 1,2,3,4,5,6,7,8 | 1 |
| `m7i.8xlarge` | 16 | 16 | 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16 | 1 |
| `m7i.12xlarge` | 24 | 24 | 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24 | 1 |
| `m7i.16xlarge` | 32 | 32 | 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32 | 1 |
**Memory optimized instances**
| Instance type | Default vCPUs | Default CPU cores | Valid CPU cores | Valid threads per core |
| --- | --- | --- | --- | --- |
| `r7i.large` | 2 | 1 | 1 | 2 |
| `r7i.xlarge` | 4 | 2 | 2 | 2 |
| `r7i.2xlarge` | 4 | 4 | 1,2,3,4 | 1 |
| `r7i.4xlarge` | 8 | 8 | 1,2,3,4,5,6,7,8 | 1 |
| `r7i.8xlarge` | 16 | 16 | 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16 | 1 |
| `r7i.12xlarge` | 24 | 24 | 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24 | 1 |
| `r7i.16xlarge` | 32 | 32 | 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32 | 1 |
# Setting the CPU cores and threads per CPU core for a DB instance class
You can configure the number of CPU cores and threads per core for the DB instance class when you perform the following operations:
+ [Creating an Amazon RDS DB instance](USER_CreateDBInstance.md)
+ [Modifying an Amazon RDS DB instance](Overview.DBInstance.Modifying.md)
+ [Restoring to a DB instance](USER_RestoreFromSnapshot.md)
+ [Restoring a DB instance to a specified time for Amazon RDS](USER_PIT.md)
**Note**
When you modify a DB instance to configure the number of CPU cores or threads per core, there is a brief outage similar to when you modify the instance class.
Set the CPU cores by using the AWS Management Console, AWS CLI or the RDS API.
## Console
**To set the cores**
1. Sign in to the AWS Management Console and open the Amazon RDS console at [https://console.aws.amazon.com/rds/](https://console.aws.amazon.com/rds/).
1. Choose **Create database**.
1. When setting the **Instance configuration** options:
1. Choose the **Optimize CPU** option.
1. Set your **vCPU** option by choosing the number of cores.
![\[Database create page when setting OCPU settings\]](http://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/images/OCPU-screenshot.png)
1. After completing other selections, select **Create database**.
## AWS CLI
**To set the cores**
1. To configure Optimize CPU using the AWS CLI, include the `--processor-features` option in the command. Specify the number of CPU cores with the `coreCount` and `threadsPerCore` as `1`.
1. Use the following syntax:
```
aws rds create-db-instance \
--engine sqlserver-ee \
--engine-version 16.00 \
--license-model license-included \
--allocated-storage 300 \
--master-username myuser \
--master-user-password xxxxx \
--no-multi-az \
--vpc-security-group-ids myvpcsecuritygroup \
--db-subnet-group-name mydbsubnetgroup \
--db-instance-identifier my-rds-instance \
--db-instance-class db.m7i.4xlarge \
--processor-features "Name=coreCount,Value=6" "Name=threadsPerCore,Value=1"
```
**Example of viewing valid processor values for a DB instance class**
Use the `describe-orderable-db-instance-options` command to show the default vCPUs, cores, and threads per core. For example, the output for the following command shows the processor options for the db.r7i.2xlarge instance class.
```
aws rds describe-orderable-db-instance-options --engine sqlserver-ee \
--db-instance-class db.r7i.2xlarge
Sample output:
-------------------------------------------------------------
| DescribeOrderableDBInstanceOptions |
+-----------------------------------------------------------+
|| OrderableDBInstanceOptions ||
|+------------------------------------+--------------------+|
|| DBInstanceClass | db.r7i.2xlarge ||
|| Engine | sqlserver-ee ||
|| EngineVersion | 13.00.6300.2.v1 ||
|| LicenseModel | license-included ||
|| MaxIopsPerDbInstance | ||
|| MaxIopsPerGib | ||
|| MaxStorageSize | 64000 ||
|| MinIopsPerDbInstance | ||
|| MinIopsPerGib | ||
|| MinStorageSize | 20 ||
|| MultiAZCapable | True ||
|| OutpostCapable | False ||
|| ReadReplicaCapable | True ||
|| StorageType | gp2 ||
|| SupportsClusters | False ||
|| SupportsDedicatedLogVolume | False ||
|| SupportsEnhancedMonitoring | True ||
|| SupportsGlobalDatabases | False ||
|| SupportsIAMDatabaseAuthentication | False ||
|| SupportsIops | False ||
|| SupportsKerberosAuthentication | True ||
|| SupportsPerformanceInsights | True ||
|| SupportsStorageAutoscaling | True ||
|| SupportsStorageEncryption | True ||
|| SupportsStorageThroughput | False ||
|| Vpc | True ||
|+------------------------------------+--------------------+|
||| AvailabilityZones |||
||+-------------------------------------------------------+||
||| Name |||
||+-------------------------------------------------------+||
||| us-west-2a |||
||| us-west-2b |||
||| us-west-2c |||
||+-------------------------------------------------------+||
||| AvailableProcessorFeatures |||
||+-----------------+-----------------+-------------------+||
||| AllowedValues | DefaultValue | Name |||
||+-----------------+-----------------+-------------------+||
||| 1,2,3,4 | 4 | coreCount |||
||| 1 | 1 | threadsPerCore |||
||+-----------------+-----------------+-------------------+||
```
In addition, you can run the following commands for DB instance class processor information:
+ `describe-db-instances` – Shows the processor information for the specified DB instance
+ `describe-db-snapshots` – Shows the processor information for the specified DB snapshot
+ `describe-valid-db-instance-modifications` – Shows the valid modifications to the processor for the specified DB instance
In the output of the preceding command, the values for the processor features are `null` if Optimize CPU is not configured.
**Example of setting the number of CPU cores for a DB instance**
The following example modifies *mydbinstance* by setting the number of CPU cores to 4 threadsPerCore as 1. Apply the changes immediately by using `--apply-immediately`. If you want to apply the changes during the next scheduled maintenance window, omit `--apply-immediately option`.
```
aws rds modify-db-instance \
--db-instance-identifier mydbinstance \
--db-instance-class db.r7i.8xlarge \
--processor-features "Name=coreCount,Value=4" "Name=threadsPerCore,Value=1" \
--apply-immediately
```
**Example of returning to default processor settings for a DB instance**
The following example modifies *mydbinstance* by returning it to the default processor values for it.
```
aws rds modify-db-instance \
--db-instance-identifier mydbinstance \
--db-instance-class db.r7i.8xlarge \
--use-default-processor-features \
--apply-immediately
```