Amazon Simple Storage Service (Amazon S3) is an extensively scalable data storage system that permits users to stock up and retrieve any amount of data at any given time. It enables secure, durable and scalable object storage that is easy to use and has a simple web service interface to store and retrieve data. One of the features that Amazon S3 provides to ensure the durability of your objects is Cross-Region Replication (CRR). Configuring Amazon S3 Cross-Region Replication is an important task in the AWS Certified SysOps Administrator – Associate exam (SOA-C02).
Cross-Region Replication (CRR) allows you to replicate data between buckets in different AWS Regions. It is a bucket-level feature which can help ensure that your data is available in another region in case of region-specific failures. It can also help to reduce latency by enabling you to maintain replicated copies of your data in Regions that are geographically closer to your users.
Configuring S3 Cross-Region Replication
Before you start configuring Cross-Region Replication, ensure that the buckets involved in the replication process satisfy the following prerequisites:
- Both source and destination buckets must have versioning enabled.
- The AWS Identity and Access Management (IAM) role for replication must have permissions to replicate objects.
- The bucket owner must have permissions to replicate objects and their ACLs.
Here is a step-by-step guide on how to configure S3 Cross-Region Replication:
Step 1: Enable versioning for both the source and destination buckets
You can enable versioning by navigating to the Properties section for each bucket and then selecting the ‘Versioning’ card. You then have the choice to ‘Enable Versioning’.
Step 2: Set up the necessary IAM roles to allow S3 to replicate objects on behalf of the bucket owner
You can create a new role from the IAM console by selecting ‘Roles’ and then ‘Create role’. Select ‘S3’ as the service that will use this role and then choose ‘Replicate objects and their ACLs between buckets’.
Step 3: Set up Cross-Region Replication for the source bucket
To enable Cross-Region Replication, go to the Management tab of the source bucket. Choose ‘Replication’ and then add a new rule. You’ll need to specify a destination bucket and also the IAM role that you created earlier. This role allows S3 to replicate objects on your behalf.
All these steps are sufficient to set up basic Cross-Region Replication. After these steps, all new objects uploaded to the source bucket will be replicated into the destination bucket.
However, remember that by default, S3 does not replicate existing objects present in the source bucket at the time of enabling replication. Also, it does not replicate any object deletions that occur in the source bucket.
Amazon S3 Cross-Region Replication is a crucial tool for data durability and availability. Understanding how to accurately configure it is a vital skill for the AWS Certified SysOps Administrator exam.
Practice Test
True or False: Enabling cross-region replication in Amazon S3 can reduce latency.
- 1) True
- 2) False
Correct Answer: True
Explanation: By replicating data across multiple regions, you can serve data from the region closer to the end users to minimize latency.
True or False: Amazon S3 Cross-Region Replication allows replicating data between two buckets that are in different AWS accounts.
- 1) True
- 2) False
Correct Answer: True
Explanation: Amazon S3 CRR can replicate data between buckets that are in same or different AWS accounts.
Amazon S3 cross-region replication (CRR) allows replication of:
- A. Existing objects in the source bucket
- B. New objects added to the source bucket
- C. Specific object versions
- D. All versions of every object
Correct Answer: B, C, and D
Explanation: Items added to the bucket after enabling CRR, Specific object versions, as well as all versions of every object in the bucket can be replicated. Existing objects aren’t automatically replicated when you set up CRR.
Multiple-choice: Which of the following does NOT trigger a replication when added to or changed in your source bucket?
- A. New objects
- B. Renamed objects
- C. Deleted objects
- D. Object ACLs
Correct Answer: B. Renamed objects
Explanation: Renaming an object is the equivalent of a delete and an add, and will not trigger a replication.
Which of the following is not supported by Amazon S3 Cross-Region Replication?
- A. Replicating within the same region.
- B. Replicating between two AWS accounts.
- C. Replicating new objects added to a bucket.
- D. Replicating existing objects in a bucket.
Correct Answer: A. Replicating within the same region.
Explanation: Cross-region replication means that the replication occurs between buckets that are in different regions.
True or False: When you enable cross-region replication for a bucket, all current objects in the bucket are immediately replicated to the destination bucket.
- 1) True
- 2) False
Correct Answer: False
Explanation: Cross-region replication only affects objects that were added after it was enabled. Existing objects are not automatically replicated.
Multiple-choice: What is the prerequisite for enabling cross-region replication?
- A. Two buckets in different regions
- B. Versioning must be enabled in both source and destination bucket
- C. IAM role to allow Amazon S3 to replicate objects
- D. All the above
Correct Answer: D. All the above
Explanation: All listed items are required to enable the cross-region replication.
True or False: Cross-region replication in Amazon S3 can help businesses meet compliance and sovereignty requirements by keeping a replica of their data in a different geographical location.
- 1) True
- 2) False
Correct Answer: True
Explanation: CRR can help owners to meet compliance and sovereignty requirements by keeping a replica of their data in a different geographical location.
True or False: CRR works even if versioning in the source bucket is suspended.
- 1) True
- 2) False
Correct Answer: False
Explanation: Versioning has to be turned on in both source and destination buckets for the CRR to function.
Which AWS management tool can you use to configure CRR in Amazon S3?
- A. AWS Management Console
- B. AWS CLI
- C. AWS SDKs
- D. All of the above
Correct Answer: D. All of the above
Explanation: AWS allows you to set up and manage CRR using any of the listed tools.
Interview Questions
What is Amazon S3 Cross-Region Replication (CRR)?
Amazon S3 Cross-Region Replication (CRR) is a bucket-level feature that enables automatic, asynchronous copying of objects across buckets in different AWS Regions.
How do you enable Amazon S3 Cross-Region Replication (CRR)?
You can enable CRR by adding a replication configuration to your source bucket. The configuration specifies the destination bucket where you want Amazon S3 to replicate objects.
Which AWS resource is needed for S3 Cross-Region Replication (CRR) to function correctly?
An IAM role is required for S3 Cross-Region Replication to function correctly. This role grants Amazon S3 the required permissions to replicate objects on behalf of your AWS account.
Can you replicate existing objects in a bucket when you set up Cross-Region Replication (CRR)?
No, Cross-Region Replication (CRR) does not replicate existing objects by default. It only applies to objects created after you set up replication.
Does S3 Cross-Region replication support replicating objects encrypted with AWS KMS?
Yes, you can use Amazon S3 Cross-Region replication (CRR) to replicate objects encrypted with AWS KMS, however, the necessary permissions must be in place.
What is important to note regarding the deletion of objects in the context of Amazon S3 Cross-Region Replication?
If an object is deleted in the source bucket, the same object will not be deleted in the destination bucket unless the delete marker replication feature is enabled.
What happens if the Replication rule is disabled in Amazon S3 Cross-Region Replication?
If you disable a replication rule in Amazon S3 Cross-Region Replication, the objects will no longer be replicated to the destination bucket. However, previously replicated objects will remain in the destination bucket.
What is a limitation of Amazon S3 Cross-Region Replication (CRR)?
A limitation of Amazon S3 Cross-Region Replication (CRR) is that it does not support direct object replication between two different accounts.
Does the replicated data in the destination bucket incur charges?
Yes, data transfer and storage charges are incurred for the replicated data in the destination bucket.
How can you monitor the progress or check the status of S3 Cross-Region Replication?
You can use Amazon S3 event notifications and Amazon CloudWatch metrics to monitor the progress and check the status of S3 Cross-Region Replication.
Is it possible to replicate objects to multiple buckets in different AWS Regions with S3 Cross-Region Replication?
No, as of now, objects can only be replicated to one destination bucket in a different AWS Region from the source bucket.
Can both source and destination buckets for CRR be owned by one AWS account?
Yes, both the source and destination buckets for Cross-Region Replication can be owned by one AWS account.
What happens in Cross-Region Replication if the same object is added in the source and destination bucket simultaneously?
The object put operation in the source bucket would be replicated to the destination bucket, and the object in the destination bucket will be overwritten.
Does Cross-Region Replication support the transfer of object ownership?
No, Cross-Region Replication does not support the transfer of ownership because the owner of the source object will also own the replicated object in the destination bucket.
What types of operations on objects can trigger Cross-Region Replication?
Cross-Region Replication can be triggered by a PUT, POST, or COPY operation on an object. It is also triggered by other API operations that create object versions, including object overwrites and deletes.
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