Enabling ARS for Oracle Database@AWS: A Guide to Benefits and Overcoming Limit Issues

 

What is Oracle ARS?

ARS is a fully managed backup and recovery service based on the proven Zero Data Loss Recovery Appliance (ZDLRA) technology.

• Problem: Traditional backups can lead to data loss between scheduled intervals (RPO) and slow recovery times (RTO).
• Solution: ARS offers real-time transaction protection, reducing RPO to less than one second.

Key Benefits (Why ARS is recommended?)

• Zero Data Loss: Real-time redo transport ensures even the most recent transactions are protected.
• Incremental Forever Strategy: Only changes are backed up after the initial full backup, reducing database overhead and network traffic.
• Backup Immutability: Includes a retention lock feature to protect against ransomware and accidental deletion.
• Cloud Simplicity: Integrated directly into the OCI Console for "one-click" enablement

Prerequisites :

The minimum supported Oracle Database versions for using ARS within the Oracle Database@AWS framework are:

• Oracle Database 19c: Minimum version is 19.18 RU (Release Update) or later.
• Oracle Database 23ai: Minimum version is 23.4 or later.

[!IMPORTANT] While the engine itself might support older versions in standard OCI, Oracle database@AWS implementation specifically requires these higher Release Updates to handle the unique networking and integration layers (like AWS VPC Lattice and the Recovery Service Subnets) that facilitate the connection between AWS and OCI.

Backup Destination Options in Oracle Database@AWS

When you are configuring your database (Exadata or Autonomous AI Database) on AWS, you generally have three choices for backup destinations:

Destination	Best For	Storage Location
Autonomous Recovery Service (ARS)	Recommended. Real-time protection, zero data loss (RPO < 1s).	OCI (Managed)
Amazon S3	Default durability (11 nines), native AWS integration.	AWS (S3 Bucket)
OCI Object Storage	Standard cloud-native backups for OCI-heavy workflows.	OCI (Object Storage)

While configuring the backup destination for Oracle Database@AWS using ARS, I encountered a common roadblock: a 'Service limit exceeded' error. This indicates that the Autonomous Recovery Service (ARS) is not yet provisioned for the tenancy, requiring a Service Request (SR) to Oracle Support to increase the storage limits.

How to Request an OCI Service Limit Increase for ARS: 

Step 1: From Database backups section, Click on right side question mark shown as below

Step 2: We can find Request a limit increase option Bottom right

Step 3: Click Limit Increase twice

Step 3: Select your subscription and Service category as a Autonomous Recovery Service  then Resource.

When submitting your reuqeust, focus on these two critical resources: 

Protected Database Count: The total number of database instances you plan to back up.

Reserved Storage (GB): The total storage capacity required to maintain your recovery window.

You can request both in a single ticket or submit them separately. Be sure to include your specific business case or migration timeline in the 'Reason for Request' field to help the Oracle team understand your requirements.

Calculating Your ARS Storage:

When requesting a service limit for Autonomous Recovery Service (ARS), you should estimate the storage needed for your backups and retention requirements. Since OCI follows a pay-as-you-use model, there is no financial penalty for having a higher allocated limit; you are only billed for actual consumption. However, Oracle periodically reviews these limits. If your actual usage is significantly lower than your allocation, Oracle may proactively reduce the limit. Should your data needs grow later, you can simply submit another Service Request (SR) to scale your storage (measured in GBs) back up.

Note: While creating CAM ticket we can add more than one request using +Additional Request option

Step 4: Once you click Create Support Request, a Cloud Account Management (CAM) request will be generated. You can track the status of this request and follow up with Oracle Support directly through this dashboard.

While these requests are typically fulfilled within 24 hours, you can expedite the process by reaching out directly to Oracle Support if you have a pending deployment.