Concepts
Amazon Simple Storage Service (Amazon S3) is a scalable object storage service that allows you to store and retrieve any amount of data at any time. One of its powerful features is Cross-Region Replication (CRR), which automatically replicates data across different AWS regions, providing enhanced data protection and geographic redundancy.
Step 1: Choose Your Source and Destination Buckets
Decide which S3 bucket will serve as your source (the bucket where the original data resides) and which will be the destination (the bucket where the data will be replicated).
Note:
- Both the source and destination buckets must have versioning enabled.
- The destination bucket can be in the same AWS account or a different AWS account.
Step 2: Enable Versioning
For CRR to function, you need to have versioning enabled on both the source and destination buckets. This preserves the version history of your objects, allowing replication to work properly.
To enable versioning, use the following AWS CLI command:
aws s3api put-bucket-versioning –bucket your-source-bucket –versioning-configuration Status=Enabled
aws s3api put-bucket-versioning –bucket your-destination-bucket –versioning-configuration Status=Enabled
Step 3: Set Up Permissions
If the destination bucket is in a different AWS account, you’ll need to update the bucket policy to grant the source bucket’s account permission to replicate objects.
Here’s an example bucket policy for the destination bucket that grants permissions:
{
“Version”: “2012-10-17”,
“Statement”: [
{
“Effect”: “Allow”,
“Principal”: {“AWS”: “arn:aws:iam::source-account-id:root”},
“Action”: [
“s3:GetBucketVersioning”,
“s3:PutBucketVersioning”,
“s3:ReplicateObject”,
“s3:ReplicateDelete”,
“s3:ReplicateTags”,
“s3:GetObjectVersionTagging”
],
“Resource”: [
“arn:aws:s3:::destination-bucket”,
“arn:aws:s3:::destination-bucket/*”
]
}
]
}
Replace source-account-id with the AWS account ID of your source bucket and destination-bucket with the bucket name where you want to replicate your objects.
Step 4: Create a Replication Rule
Next, you need to create a replication rule on the source bucket. This rule defines what objects to replicate and where they should be replicated.
Through the AWS Management Console:
- Navigate to the S3 bucket.
- Choose ‘Management’ and then ‘Replication’.
- Click ‘Add rule’.
- Choose the scope of the objects (which objects to replicate).
- Set the destination bucket, specifying the account and the storage class (if different from the source).
Alternatively, you could use the AWS CLI:
aws s3api put-bucket-replication –bucket your-source-bucket –replication-configuration ‘{
“Role”: “arn:aws:iam::source-account-id:role/replication-role”,
“Rules”: [{
“Status”: “Enabled”,
“Priority”: 1,
“DeleteMarkerReplication”: {“Status”: “Enabled”},
“Filter”: {},
“Destination”: {
“Bucket”: “arn:aws:s3:::destination-bucket”,
“StorageClass”: “STANDARD_IA”
}
}]
}’
Note that replication-role refers to an IAM role with the necessary permissions to perform the replication.
Step 5: Monitor the Replication
Once set up, you can monitor the status of your replication tasks. Each object replicated by CRR will have a replication status associated with it. This can be checked via the AWS Management Console or the AWS CLI.
Considerations for Cross-Region Replication
- Storage Costs: Be aware that storing replicated data in another region will incur additional storage costs.
- Data Transfer Costs: Replicating data across regions will also incur data transfer costs.
- Latency: Depending on the distance between the regions, there may be some latency in replication.
- Eventual Consistency: CRR is an eventually consistent process, which means there might be a short delay between the time the original object is uploaded and when the replica appears in the destination bucket.
Advanced Options
CRR also allows for more complex configurations such as replicating to multiple destination buckets and filtering which objects to replicate based on prefixes, tags, or object size.
Conclusion
Configuring CRR in Amazon S3 adds a layer of redundancy and protection to your data in case of regional outages or accidental deletions. By following the steps outlined in this tutorial, AWS Certified SysOps Administrators can set up CRR to meet specific business continuity and disaster recovery requirements.
Remember always to test your replication setup to ensure that it meets your expected Recovery Point Objectives (RPO) and Recovery Time Objectives (RTO).
Answer the Questions in Comment Section
True or False: Cross-Region Replication (CRR) can replicate objects across S3 buckets located in different AWS regions in real-time.
- (A) True
- (B) False
Answer: A
Explanation: CRR is used to replicate objects across S3 buckets in different AWS regions and it begins replicating objects as soon as the source object is uploaded.
Which of the following are prerequisites for configuring Cross-Region Replication on an S3 bucket? (Select TWO)
- (A) Versioning must be enabled on both the source and destination buckets.
- (B) The source and destination buckets must be in the same AWS account.
- (C) The buckets must have public read permissions.
- (D) IAM permissions must allow S3 to replicate objects on your behalf.
- (E) Cross-Origin Resource Sharing (CORS) must be enabled.
Answer: A, D
Explanation: Versioning must be enabled on both buckets involved in replication and the IAM permissions must allow S3 to replicate objects from the source to the destination bucket.
True or False: Deleting an object in the source bucket will delete the replica in the destination bucket when cross-region replication is enabled.
- (A) True
- (B) False
Answer: B
Explanation: By default, deleting an object in the source bucket does not delete the replica in the destination bucket when CRR is enabled. However, you can set a replication time control to replicate delete markers if needed.
In which of the following scenarios will S3 Cross-Region Replication not replicate an object? (Single Select)
- (A) If the object in the source bucket is encrypted with SSE-S
- (B) If the object in the source bucket has public read permissions.
- (C) If the object is created by a lifecycle policy in the source bucket.
- (D) If the source and destination buckets have different storage classes.
Answer: C
Explanation: Objects created as a result of a lifecycle policy, such as a reduced redundancy storage (RRS) object transitioning to Standard storage class, are not replicated through CRR.
True or False: After setting up Cross-Region Replication, all previously existing objects in the source bucket are automatically replicated to the destination bucket.
- (A) True
- (B) False
Answer: B
Explanation: Only objects created or updated in the source bucket after the replication rule is added are replicated. Existing objects must be copied manually or by re-uploading them.
The owner of the destination bucket for cross-region replication must grant the source bucket owner which permission in the bucket policy?
- (A) s3:PutObject
- (B) s3:GetObject
- (C) s3:ReplicateObject
- (D) s3:ListBucket
Answer: C
Explanation: The owner of the destination bucket must add a bucket policy that grants the source account permission to replicate objects (s3:ReplicateObject).
Can you use the AWS CLI to configure Cross-Region Replication for an S3 bucket?
- (A) Yes
- (B) No
Answer: A
Explanation: The AWS CLI can be used to configure Cross-Region Replication by running appropriate ‘aws s3api’ commands.
Which of the following events can trigger Cross-Region Replication for an object?
- (A) Uploading an object to the source bucket.
- (B) Updating an object’s metadata in the source bucket.
- (C) Updating an object’s ACL in the source bucket.
- (D) All of the above.
Answer: D
Explanation: All these actions can trigger replication as long as the replication rules are set up to handle them.
True or False: The replication configuration must be added to the source bucket.
- (A) True
- (B) False
Answer: A
Explanation: The replication configuration, which includes the destination bucket and any filters or rules for what to replicate, is added to the source bucket’s settings.
When configuring CRR, what is the purpose of setting a replication Time Control (RTC)?
- (A) To define the storage class for the replicated objects.
- (B) To guarantee a replication time for replicated objects.
- (C) To establish a schedule for when replication occurs.
- (D) To limit how many objects can be replicated in a given time.
Answer: B
Explanation: Setting a replication Time Control (RTC) provides a replication time SLA, which ensures that objects are replicated within 15 minutes of upload.
True or False: If you enable requestor pays on your source bucket, AWS charges the requestor for replication to the destination bucket.
- (A) True
- (B) False
Answer: B
Explanation: Requestor pays does not apply to the Cross-Region Replication feature. The owner of the source bucket will pay for the transfer costs associated with replication.
Which storage class is NOT applicable when setting up replication configuration in Cross-Region Replication?
- (A) STANDARD
- (B) STANDARD_IA
- (C) INTELLIGENT_TIERING
- (D) GLACIER
Answer: D
Explanation: You cannot use GLACIER as it’s a long-term archival storage class and does not support replication. However, you can replicate into a GLACIER storage class with a lifecycle policy.
Great tutorial! Helped me a lot in understanding CRR for my AWS SysOps exam.
Thanks for the detailed steps on configuring S3 Cross-Region Replication.
Quick question: Does CRR support all S3 storage classes?
What’s the latency like for CRR between different regions?
Helpful blog post. Clarified many doubts I had.
Does anyone know if there are costs associated with enabling CRR?
I am facing issues with CRR status showing ‘Failed’. Any suggestions?
Appreciate the blog. Helped me setting up my first CRR!