Troubleshooting Azure SQL Data Sync Groups Stuck in Progressing State
Azure SQL Data Sync is commonly used to synchronize data across Azure SQL Databases and on‑premises SQL Server environments. While the service works well in many scenarios, customers may occasionally encounter a situation where a Sync Group remains stuck in a “Progressing” state and cannot be started, stopped, or refreshed. This blog walks through a real-world troubleshooting scenario, highlights the root cause, and outlines practical remediation steps based on actual support investigation and collaboration. Problem Overview In this scenario, the customer reported that: The Sync Group was stuck in “Progressing” for multiple days Sync operations could not be started or stopped Tables could not be refreshed or reconfigured Azure Activity Logs showed operations as Succeeded, yet sync never progressed Our backend telemetry showed the Sync Group as Active, while hub and member databases were in Reprovisioning state The last successful sync occurred on XX day, after which the sync pipeline stopped making progress. Initial Investigation Findings During the investigation, several key observations were made: 1. High DATA IO Utilization Telemetry and backend checks revealed that DATA IO utilization was pegged at 100% on one of the sync member databases starting XX day. Despite no noticeable change in application workload, the database was under sustained IO pressure, which directly impacted Data Sync operations. 2. Deadlocks During Sync Processing Our backend telemetry showed repeated deadlock errors: Transaction was deadlocked on lock resources with another process and has been chosen as the deadlock victim. These deadlocks were observed for multiple Sync Member IDs starting the same day IO saturation began. This aligned with the hypothesis that resource contention, not a Data Sync service failure, was the underlying issue. 3. Metadata Database Was Healthy The Sync metadata database was running on a serverless Azure SQL Database (1 vCore) and showed healthy resource usage, ruling it out as a bottleneck. Recommended Troubleshooting Steps Based on the findings, the following steps were recommended and validated: ✅ Step 1: Address Database Resource Constraints First Before attempting to recreate or reset the Sync Group, the focus was placed on resolving DATA IO saturation on the affected database. Actions included: Scaling up the database (DTUs / vCores) Monitoring IO utilization after scaling Ensuring sufficient headroom for sync operations This was identified as the primary remediation step. ✅ Step 2: Use the Azure SQL Data Sync Health Checker The Azure SQL Data Sync Health Checker was recommended to validate: Sync metadata integrity Table-level configuration issues Agent and connectivity status GitHub tool: AzureSQLDataSyncHealthChecker ✅ Step 3: Validate Sync Group and Agent State via PowerShell PowerShell was used to confirm: Sync Group state Last successful sync time On‑premises Sync Agent connectivity Example commands used: Get-AzureRmSqlSyncGroup ` -ResourceGroupName "ResourceGroup01" ` -ServerName "Server01" ` -DatabaseName "Database01" | Format-List Get-AzureRmSqlSyncAgent ` -ResourceGroupName "ResourceGroup01" ` -ServerName "Server01" | Select ResourceGroupName, SyncState, LastSyncTime Resolution After the customer increased the database size, DATA IO utilization dropped, sync operations resumed normally, and the customer confirmed that the issue was resolved.Why Long-Term Retention (LTR) Backups Don’t Attach After a PITR Restore in Azure SQL Database
Summary Customers sometimes expect that after performing a Point‑in‑Time Restore (PITR) and renaming the restored database back to its original name, existing Long‑Term Retention (LTR) backups will automatically appear and continue from where they left off. This behavior may have worked in older or legacy environments, but in modern Azure SQL Database deployments—especially across new servers or subscriptions—this expectation can lead to confusion. This article explains why LTR backups do not attach to restored databases, even if the database name is reused, and what customers should expect instead. The Scenario The discussion originated from a common migration pattern: A customer has an Azure SQL Database with LTR policies configured (for example, monthly backups retained for 10 years). The customer performs a Point‑in‑Time Restore (PITR) of that database. After the restore, the database is renamed to match the original database name. The customer expects the existing LTR backups to appear under the restored database. In legacy environments, this behavior appeared to work. However, in newer Azure SQL Database deployments, the LTR backups are not visible after the restore and rename process. Key Technical Detail: LTR Is Not Based on Database Name The most important concept to understand is this: LTR backups are associated with the database’s logical database ID—not the database name. Each Azure SQL Database is assigned a unique logical database ID at creation time. When a PITR restore is performed: A new database is created It receives a new logical database ID Even if you rename the database to match the original name, the logical ID remains different As a result, the restored database is treated as a completely new database from an LTR perspective, and it does not inherit the historical LTR backup chain. Why Renaming the Database Does Not Help Renaming a database only changes its display name. It does not change: The logical database ID The internal association used by the LTR system Because LTR configuration and backup visibility are tied to the logical database ID, renaming alone cannot reattach historical LTR backups. Subscription Boundaries Matter Another important clarification raised in the discussion: LTR backups are scoped to the subscription where the database was created While you can restore LTR backups to a different server within the same subscription, you cannot carry historical LTR backups across subscriptions If a customer migrates to a new subscription, the historical LTR chain from the old subscription cannot be reused or reattached. Only new LTR backups created after the move will exist in the new subscription. What Customers Will Observe After a PITR restore and rename: ✅ The database is successfully restored ✅ LTR policies can be configured again ❌ Historical LTR backups from the original database are not visible ❌ The restored database does not inherit old LTR backups, even if the name matches This is expected behavior and aligns with the current Azure SQL Database architecture. How to Validate LTR Backups Correctly To avoid confusion caused by portal caching or UI expectations, customers can list LTR backups programmatically using PowerShell or Azure CLI, as documented in Microsoft Learn: Azure SQL Database: Manage long-term backup retention Azure SQL Database: Manage long-term backup retention - Azure SQL Database | Microsoft Learn This confirms whether LTR backups exist for a specific logical database ID. Best Practices and Recommendations Do not rely on database renaming to preserve LTR history. Treat any PITR restore as a new database from an LTR perspective. If historical LTR backups must remain accessible: Keep the original database intact Restore LTR backups directly from the original database when needed Plan migrations carefully, especially when moving across subscriptions, as LTR history cannot be migrated. Final Thoughts LTR backups are a powerful compliance and recovery feature in Azure SQL Database, but they are intentionally designed to be immutable and identity‑based, not name‑based. Understanding that logical database ID—not database name—controls LTR association helps set correct expectations and avoids surprises during restores or migrations. Frequently Asked Questions (FAQ) Q1: Why don’t my existing LTR backups appear after I restore a database using PITR? Because a Point‑in‑Time Restore (PITR) creates a new database with a new logical database ID. Long‑Term Retention (LTR) backups are associated with the database’s logical ID—not its name—so the restored database does not inherit the historical LTR backup chain. Q2: If I rename the restored database to the original name, shouldn’t the LTR backups reappear? No. Renaming a database only changes its display name. It does not change the logical database ID, which is what LTR uses to associate backups. As a result, renaming does not reattach existing LTR backups. Q3: This used to work in our legacy environment—why is it different now? In older environments, the behavior may have appeared to work due to differences in platform implementation. In current Azure SQL Database architecture, LTR association is strictly identity‑based, which ensures immutability, compliance, and predictable backup behavior. Q4: Can I attach historical LTR backups to a restored database manually? No. LTR backups are immutable and cannot be reattached or reassigned to a different logical database ID. This behavior is by design. Q5: What happens if I move my database to a new subscription? LTR backups are scoped to the subscription where the database was created. If you migrate to a new subscription: Historical LTR backups from the old subscription cannot be carried over Only new LTR backups created after the move will exist in the new subscription Q6: Can I still restore from my old LTR backups? Yes. As long as the original database (or its logical identity) still exists in the original subscription, you can restore directly from those LTR backups—even if a newer database with the same name exists elsewhere. Q7: How can I verify which LTR backups actually exist? The most reliable way is to list LTR backups programmatically using Azure PowerShell or Azure CLI, which queries backups by logical database ID rather than relying solely on portal views. Refer to the official documentation: Azure SQL Database – Manage long‑term backup retention Q8: What is the recommended approach if we need long‑term recoverability after PITR? Treat every PITR restore as a new database from an LTR perspective Keep the original database intact if historical LTR backups must remain accessible Plan subscription migrations carefully, as LTR history cannot be migrated
