Wondering how to delete a Subnet that is part of an Amazon RDS DB Subnet group? We can help you.

Here, at Bobcares, we assist our customers with several AWS queries as part of our AWS Support Services.

Today, let us see how our Support Techs do that.

How to delete a subnet that is part of an Amazon RDS DB subnet group?

 
In order to launch an Amazon RDS DB instance, an RDS DB subnet group must contain at least two subnets.

These subnets must be in different Availability Zones in the same AWS Region.

You can remove or delete a subnet from the DB subnet group only if there are no DB instances associated with the subnet group and launched in the subnet that you’re trying to delete.

If you launch a DB instance with a DB subnet group that contains two subnets in two Availability Zones, then you can’t delete any subnet from the DB subnet group.

If you have a Multi-AZ deployment that has two or more subnets in a subnet group, then you can launch the DB instance in any of the subnets of the two Availability Zones.

Also, if you have a Single-AZ deployment that has two or more subnets in the subnet group, then you can specify the Availability Zone when you create a DB instance.

If you didn’t specify the Availability Zone when you created the DB instance, then the DB instance is launched in any of the subnets of the two Availability Zones.
 
 

Delete a subnet from a Single-AZ Amazon RDS DB instance

 
To delete a subnet from a DB subnet group, isolate the subnet by moving the DB instance to another subnet.

Then, remove the subnet from the DB subnet group. The following steps are applicable for Amazon RDS for Oracle, PostgreSQL, MySQL, MariaDB, or SQL Server.

Today, let us see the steps followed by Support techs to delete subnet:

1.Firstly, modify the DB instance to be a Multi-AZ deployment. This creates a standby for the DB instance in a different Availability Zone that uses a different subnet.
2.Then, reboot the DB instance with failover. This promotes the standby to the primary DB instance.
3.Modify the DB instance back to a Single-AZ DB instance.
4.Open the Amazon RDS console, and then choose Subnet groups from the navigation pane.
5.Then, choose the subnet group that the DB instance is associated with.
6.Next, choose Edit.
7.From Add subnets, select the subnet you want to delete, and then choose Remove.
8.Finally, choose Save.

[Need help with the process? We’d be happy to assist]

Conclusion

In short, we saw how our Support Techs delete a subnet that is part of an Amazon RDS DB subnet group.