# DB instance class support for RDS Custom for SQL Server
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Check if the DB instance class is supported in your Region by using the [ describe-orderable-db-instance-options](https://awscli.amazonaws.com/v2/documentation/api/latest/reference/rds/describe-orderable-db-instance-options.html) command.

RDS Custom for SQL Server supports the DB instance classes shown in the following table:


| SQL Server edition | RDS Custom support | 
| --- | --- | 
|  Enterprise Edition  |  db.r5.xlarge–db.r5.24xlarge db.r5b.xlarge–db.r5b.24xlarge db.m5.xlarge–db.m5.24xlarge db.r6i.xlarge–db.r6i.32xlarge db.m6i.xlarge–db.m6i.32xlarge db.x2iedn.xlarge–db.x2iedn.32xlarge  | 
|  Standard Edition  |  db.r5.large–db.r5.24xlarge db.r5b.large–db.r5b.8xlarge db.m5.large–db.m5.24xlarge db.r6i.large–db.r6i.8xlarge db.m6i.large–db.m6i.8xlarge db.x2iedn.xlarge–db.x2iedn.8xlarge  | 
|  Developer Edition  |  db.r5.xlarge–db.r5.24xlarge db.r5b.xlarge–db.r5b.24xlarge db.m5.xlarge–db.m5.24xlarge db.r6i.xlarge–db.r6i.32xlarge db.m6i.xlarge–db.m6i.32xlarge db.x2iedn.xlarge–db.x2iedn.32xlarge  | 
|  Web Edition  |  db.r5.large–db.r5.4xlarge db.m5.large–db.m5.4xlarge db.r6i.large–db.r6i.4xlarge db.m6i.large–db.m6i.4xlarge db.r5b.large–db.r5b.4xlarge  | 

The following recommendations apply to db.x2iedn class types:
+ At creation, local storage is a raw and unallocated device. Before using a DB instance with this instance class, you must mount and format the local storage. Afterward, configure `tempdb` on it to ensure optimal performance. For more information, see [Optimize tempdb performance in Amazon RDS Custom for SQL Server using local instance storage](https://aws.amazon.com/blogs/database/optimize-tempdb-performance-in-amazon-rds-custom-for-sql-server-using-local-instance-storage/).
+ Local storage reverts to its raw and unallocated state when you run DB instance operations such as scale compute, instance replacement, snapshot restore, or point-in-time recovery (PITR). In these situations, you must remount, reformat, and reconfigure the drive and `tempdb` to restore functionality.
+ For Multi-AZ instances, we recommend that you perform the configuration on a standby DB instance. This way, if a failover occurs, the system continues to operate without issues because the configuration is already in place on the standby instance.