Configure and manage storage accounts
📘Microsoft Certified: Azure Administrator Associate (AZ-104)
1. What Is Object Replication?
Object replication is a feature of Azure Blob Storage that enables you to copy block blobs asynchronously from:
- One container to another container
- Between two different storage accounts
- Potentially in different Azure regions
When a blob is created or updated in the source container, the changes are automatically copied to the destination container.
This replication is one-way (source → destination) unless you manually configure the opposite direction separately.
2. Why Is Object Replication Used in IT Environments?
In real IT environments, companies use object replication for:
✔ Disaster Recovery (DR)
If production storage is in Region A and the company wants backup data in Region B.
✔ Data Distribution
Applications running in multiple regions need the same data close to the users.
✔ Analytics / Reporting
Production systems write to one storage account, while analytics systems read data from another account without affecting performance.
✔ Multi-team sharing
Dev, QA, and Analytics teams work with the same data but in separate storage accounts.
3. How Object Replication Works
Step-by-step:
- A storage administrator enables object replication between two storage accounts.
- The administrator creates a replication policy defining:
- Source account and container
- Destination account and container
- New or updated block blobs in the source container are detected.
- Azure asynchronously copies those blobs to the destination container.
- You can monitor replication status for each blob.
Object replication does not require additional scripts, automation, or triggers — Azure handles everything.
4. Requirements for Enabling Object Replication (Exam Critical)
You must know these requirements for the AZ-104 exam:
✔ Supported only for Block Blobs
Page blobs or append blobs cannot be replicated.
✔ Both storage accounts must use:
- General-purpose v2 (GPv2)
- Or Blob Storage accounts
✔ Both accounts must have:
- Hierarchical Namespace disabled (so Data Lake Gen2 is not supported)
✔ Versioning must be enabled in both source and destination accounts
This allows Azure to track blob changes.
✔ Change Feed must be enabled in the source account
The change feed logs blob changes for replication.
✔ Source and destination containers must already exist
Azure does not create containers automatically.
✔ Networking configurations must allow traffic
If using private endpoints or firewalls, you must ensure both accounts can communicate.
✔ Replication does NOT work for:
- Snapshots
- Soft-deleted blobs
- Archive tier blobs
These are exam-tested limitations.
5. Important Limitations (Very Common Exam Questions)
Azure Object Replication cannot:
❌ Replicate existing blobs automatically
Only blobs created or modified after the policy is created are replicated.
❌ Replicate blob snapshots
❌ Replicate blobs in archive tier
❌ Work with Data Lake Gen2 (Hierarchical Namespace = ON)
❌ Work with any blob type other than Block Blobs
❌ Do two-way replication by default
Each direction requires a separate policy.
❌ Replicate metadata-only changes
Metadata updates do NOT trigger replication.
6. Storage Account Redundancy vs. Object Replication (Don’t Confuse!)
A common exam trap:
Object replication is NOT the same as storage redundancy (LRS, GRS, ZRS, etc.).
Redundancy
Azure automatically copies data inside a region or across paired regions. You don’t control it.
Object Replication
You manually configure copy rules between accounts and containers.
Both can exist together, but they serve different purposes.
7. How to Configure Object Replication (Portal Steps)
This process is very likely in exam questions.
Step 1 — Enable Versioning
In both source and destination storage accounts:
- Go to Data Protection
- Enable Blob versioning
- Enable Change Feed (source only)
Step 2 — Create Containers
Create matching containers (e.g., “source-data” and “replica-data”).
Step 3 — Create Replication Policy
On the source account:
- Go to Object Replication
- Select Create replication rule
- Choose destination storage account
- Choose source and destination containers
- Save the policy
Step 4 — Validate Replication
Upload a blob to the source container.
Check the destination container for the replicated blob.
8. Monitoring Replication
Azure provides replication status:
- Complete
- Pending
- Failed
- No status (for older blobs before the policy)
You can view the status:
- In the Azure Portal
- Using CLI (
az storage blob show) - Using PowerShell (
Get-AzStorageBlob) - Through Azure Monitor logs
9. Object Replication Security Considerations
✔ Identity is required
You must ensure proper IAM access:
- Role: Storage Blob Data Owner or Storage Account Contributor
✔ Firewall/Network rules
If storage accounts have restricted networks:
- Allow trusted Microsoft services
- Or use private endpoints
- Or ensure VNet rules allow access
✔ Replication is encrypted
Replication uses Azure Storage encryption automatically.
10. Common Exam Scenarios
Scenario 1:
You need to copy new data from a production storage account to an analytics storage account in another region.
Solution: Configure object replication.
Scenario 2:
A company wants to replicate all existing 5 TB of data to another account.
Answer: Object replication cannot replicate existing data.
Solution: Use tools such as AzCopy, then enable replication for future changes.
Scenario 3:
Replication not working — what to check?
- Versioning enabled?
- Change feed enabled on source?
- Hierarchical Namespace disabled?
- Block blobs used?
Scenario 4:
You require two-way synchronization.
Solution: Create two replication rules (A → B and B → A).
11. Key Points to Remember for the Exam
Memorize these:
- Works only for block blobs
- Versioning ON in both accounts
- Change Feed ON in source
- Data Lake Gen2 NOT supported
- Does not replicate existing blobs
- Does not replicate metadata-only changes
- Asynchronous replication
- Requires GPv2 or Blob Storage accounts
- Replication is one-way unless configured both ways
Conclusion
Object replication is an important feature for distributing, protecting, and synchronizing blob data across storage accounts. For the AZ-104 exam, focus on:
- Requirements
- Limitations
- Configuration steps
- Typical scenarios
- Difference from storage redundancy
Understanding these areas will help you answer exam questions confidently and accurately.
