Questions about "Availability" (HA) options when creating a read replica
Hi re:Post,
During the "Create read replica > Availability > Deployment " options we are given (3) selections.
The 2nd was explained to me in another post (thank you again!), but we chose the 3rd option in setting up our replica, ie: "Single DB Instance": "Creates a writer DB instance with no reader DB instances".
1a) Where is this "writer DB instance"?
1b) Is our replica db (db-demo-replica/Oregon) still read-only?
1c) Is there a way to create a read only replica without creating another HA instance in addition to the read replica instance?
Additionally, during the "Create read replica > Additional Configuration > Backups"
2a) Where is the check box to enable backups?
Because post replica creation, we see that Automated backups are disabled:
2b) How do we enable Automated backups during the "Create read replica" process? (We see that it can be enabled after the read replica is created but it seems like extra work to go back and do enable this after setup. We may have hundreds of replicas to create and do not want to have to add another step for every setup).
Thank you for your time and help!
Best Regards,
Donald
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asked 2 years ago217 views
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Thank you for your detailed questions about read replicas in Amazon RDS. I'll address each of your points:
1a) The "writer DB instance" in this context refers to the read replica itself. When you choose "Single DB Instance," you're creating a standalone read replica that can be promoted to a writable instance if needed.
1b) Yes, your replica db (db-demo-replica/Oregon) is still read-only by default. Read replicas are created as read-only copies of the source DB instance.
1c) Yes, you can create a read-only replica without creating another HA instance. The "Single DB Instance" option you chose does exactly this - it creates a read replica without additional HA infrastructure.
2a) There isn't a checkbox to enable backups during the read replica creation process. Read replicas are created with backups disabled by default.
2b) Unfortunately, you cannot enable automated backups during the "Create read replica" process. Automated backups must be enabled after the read replica is created. This is a limitation of the current RDS implementation.
To streamline the process of creating multiple replicas with backups enabled, you might consider using AWS CLI or AWS SDKs to automate the creation of read replicas and the subsequent enabling of automated backups. This would allow you to create replicas and enable backups in a single workflow, reducing the manual steps required.
It's worth noting that while backups are disabled on read replicas by default, it's generally recommended to enable them, especially if you plan to promote the read replica to a standalone instance in the future or if you need point-in-time recovery capabilities for the replica.
If you need to create hundreds of replicas, I strongly recommend exploring automation options using AWS CLI, SDKs, or infrastructure-as-code tools like AWS CloudFormation or Terraform to manage this process efficiently and consistently.
Sources
Creating a read replica - Amazon Relational Database Service
Promoting a read replica to be a standalone DB instance - Amazon Relational Database Service
Working with DB instance read replicas - Amazon Relational Database Service
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