Hi,

Here are FAQs:

Q - When are these instances being deprecated? • We will be grouping the migration of RDS for MySQL, MariaDB and PostgreSQL database instances running on M4, R4, or T2 instance types into two rounds. • Accounts that do not have associated reserved instances will start from June 1, 2024. • Accounts with associated reserved instances will start from September 1, 2024.

Q - Which instance type(s) will my database be auto-migrated to? • We will make our best effort to migrate your database instance from M4→M5, R4→R5 and T2→T3 and keep its original sizes. • In cases that we cannot keep the original size, we will attempt to migrate your database instance to one size smaller than its original size. We have only identified M4.10xlarge as having no equivalent size and will migrate that to M5.8xlarge. Reserved instances (RIs) associated with M4.10xlarge will be cancelled after we have migrated that account’s M4.10xlarge DB instance to M4.8xlarge.

Q - Do I have to be on a particular engine version to be auto-migrated? • We have removed requirements to be on a particular engine version. If your database is on a M4/R4/T2 instance types, we will try to upgrade them.

Q - What can I expect when my database instance upgrade? • For accounts without active RDS MySQL, MariaDB and PostgreSQL M4, R4, or T2 reserved instances, starting June 1, 2024, RDS will set a parameter to ‘modify RDS MySQL, MariaDB, and PostgreSQL M4/R4/T2 DB instance to M5/R5/T3’. • The database instance will update during your scheduled maintenance period. If by chance your database instance is still on M4, R4 or T2 instances following your scheduled maintenance period, on our second attempt, we will directly apply the changes. • For more information on how DB instances are modified, please see Modifying an Amazon RDS DB instance.

Q - How will Reserved Instance (RI) migration work with DB instance upgrade: • The RI migration and DB instance upgrade are two separate processes that run after one another. RDS will work through each region and find all M4/R4/T2 RI contracts and create corresponding M5/R5/T3 RI contracts. Then RDS will work through each region and find all M4/R4/T2 DB instances and insert an action to “modify” the instance type. During your maintenance window, the M4/R4/T2 DB instances will update to a M5/R5/T3 DB instance. After all DB instances are updated, we will cancel the old M4/R4/T2 RI contracts.

Q - When is the exact date of my auto-upgrade? • Due to a large number of instances that require an upgrade, we are not able to provide a date on when your upgrade will happen.

Q - What if I have RIs covering my databases and it expires before my auto-migration happens? • You will incur some on-demand charges until you purchase the RI to cover the database instance. • If your RIs expire and you have not been auto-upgrade, we recommend you to self-upgrade your database(s) and purchase RIs to cover your upgraded database(s).

Q - Will there be a downtime? If yes, how long? • Yes, there will be some downtime. Downtime will depend on the size of customer's instance/database. It can be anywhere from 5 minutes to 60 minutes, but typically less than 30 minutes. If a customer configures their instances as Multi-AZ, each database instance will be down one at a time.

Q - What if I want to self-upgrade my database instances but I am not sure how to? • For help migrating your Amazon RDS instances to an alternate AZ, please refer to the 'How do I move an Amazon RDS instance out of an Availability Zone?' re:Post article. • You may consider using RDS Blue Green Deployments for RDS MySQL and RDS PostgreSQL to seamlessly upgrade your database's instance type or engine version. • Directly change your DB instance type by Modifying an Amazon RDS DB instance.

Q - My engine version needs to be upgraded; can I upgrade both on my own? • You may upgrade both the engine version and instance type at the same time. Directly change your DB instance type by Modifying an Amazon RDS DB instance. For additional details, refer to AWS CLI command reference modify-db-instance options parameter ‘db-instance-class’ and ‘engine-version’.

Q - Will the RI upgrade process cause additional RI charges? • To cover the old and new DB instance during the migration period, our RI upgrade process creates a RI of the new DB instance type matching your old RI contract terms and rates. During your upgrade month, you may see two RI line items. However, only one of the RIs will charge the actual fixed usage rate, if applicable, at any one time, either the old DB instance RI usage rates or the new instance RI usage rates. After we migrate your DB instance, we will cancel the old RI contracts. • Your migrated RI’s will only incur one fixed usage charge, if applicable, at the RI public rates, which can be found on Amazon Relational Database Service pricing page.

Refer following summary:

Starting January 19, 2024, Amazon RDS will begin disabling the creation of new On Demand instances for Amazon RDS for MySQL, MariaDB, and PostgreSQL database instances running on M4, R4, or T2 instance types. And starting on May 1, 2024, Amazon RDS will begin upgrading MySQL, MariaDB, and PostgreSQL database instances running on M4, R4, or T2 instance types to a newer generation instance type.

We strongly recommend that you migrate your existing database instances running M4, R4, and T2 instance types to newer generation instance types before April 30, 2024. You may use the following recommendation:

• Upgrade M4 instance to M6i instance
• Upgrade R4 instance to R6i instance
• Upgrade T2 instance to T3 instance

Depending on the instance type you choose to upgrade to, you may also need to upgrade your MySQL, MariaDB, or PostgreSQL database version. We recommend that you also upgrade your database engine to the following version:

• MySQL - 8.0.28 or higher
• MariaDB - 10.4.26 or higher
• PostgreSQL - 13.4 or higher

For more details on supported RDS DB instance classes for each engine version please refer to the Amazon RDS user guide [1]. We also recommend using RDS Blue Green Deployments [2] to upgrade your database engine version.

How will my Reserved Instances (RIs) be impacted?

If you upgrade instances that are receiving a billing benefit from RIs, the RIs will no longer cover the instances and you may see additional on-demand charges on your bill. To avoid this, we recommend the following:

• If you have no RIs OR if your RIs have expired, you should migrate your instances at the earliest convenience.
• If you have active RIs which expire before May 1, 2024, you should wait for the RIs to expire and then migrate your instances. You can then purchase new RIs for the upgraded instance types.

- If you have RIs which will be active after April 30, 2024, you should not migrate your instances. RDS will automatically upgrade database instances and RIs that are active after April 2024. However, your RDS instances MUST be on the DB engine version above. Your database instances and RIs will be migrated to M6i, R6i, or T3 instances depending on their current instance type.

If you have any questions or concerns, please contact AWS Premium Support [2].

[1] https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/Concepts.DBInstanceClass.html

[2] https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/blue-green-deployments.html

[3] https://aws.amazon.com/support

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Hope you find this helpful.

Comment here if you have additional questions. Happy to help.

-- Abhishek