Edit review "performance-degradation-misaligned-io-sector-error.md"

Author: v-phoebh

support/sql/database-engine/performance/performance-degradation-misaligned-io-sector-error.md

@@ -1,15 +1,15 @@
 ---
 title: Performance Degradation from Misaligned I/O Sector Size Error
-description: This article describes how to resolve misaligned I/O operations due to sector size mismatch in SQL Server.
+description: This article describes how to resolve misaligned I/O operations due to sector size mismatches in SQL Server.
 ms.author: dpless
 author: dplessMSFT
 ms.reviewer: mathoma, v-sidong
 ms.date: 03/20/2025
 ms.custom: sap:Installation, Patching, Upgrade, Uninstall
 ---
-# Performance degradation from misaligned I/O sector size error in SQL Server
+# Performance degradation caused by misaligned I/O sector size errors in SQL Server
 
-_Original product version:_   SQL Server  
+_Applies to:_   SQL Server  
 
 This article introduces how to resolve performance degradation due to misaligned I/O operations in SQL Server when the physical sector size differs between disk drives. 
 
@@ -22,11 +22,11 @@ SQL Server can encounter misaligned I/O operations when the physical sector size
 - Log shipping
 - Hardware migrations 
 
-For instance, a common issue occurs when the primary server uses a 4-KB sector size, while the secondary uses 512 bytes, leading to misaligned I/O operations during log synchronization or restore processes. This misalignment can result in performance degradation, such as slow restores or synchronization delays.
+For instance, a common issue occurs when the primary server uses a 4-KB sector size while the secondary server uses 512 bytes. This issue causes misaligned I/O operations during log synchronization or restore processes. This misalignment can result in performance degradation, such as slow restores or synchronization delays.
 
-[Trace Flag 1800](/sql/t-sql/database-console-commands/dbcc-traceon-trace-flags-transact-sql#tf1800) ensures that SQL Server uses a consistent 4-KB sector size for transaction log I/O operations, regardless of the underlying disk's physical sector size. This trace flag is designed to maintain performance in mixed environments, where servers might have been upgraded or migrated to hardware with different storage specifications.
+[Trace Flag 1800](/sql/t-sql/database-console-commands/dbcc-traceon-trace-flags-transact-sql#tf1800) ensures that SQL Server uses a consistent 4-KB sector size for transaction log I/O operations, regardless of the underlying disk's physical sector size. This trace flag is designed to maintain performance in mixed environments where servers might have been upgraded or migrated to hardware with different storage specifications.
 
-For databases with write-intensive workloads, aligning I/O operations can provide significant performance improvements, whereas the benefits might be negligible in read-intensive environments.
+For databases with write-intensive workloads, aligning I/O operations can significantly improve performance, whereas the benefits might be negligible in read-intensive environments.
 
 ## Symptoms
 
@@ -35,39 +35,39 @@ You might experience performance degradation in SQL Server due to misaligned I/O
 - **Slow synchronization or restore times**: Misaligned I/O operations can result in slower synchronization or restore times, especially in distributed SQL Server environments, such as Always On availability groups or log shipping. 
 - **Error messages in the SQL Server error log**: Error messages related to I/O operations can indicate misalignment issues, such as: 
 
-   `There have been # misaligned log IOs which required falling back to synchronous IO`
+   `There have been # misaligned log IOs which required falling back to synchronous IO.`
 
-- **Performance bottle necks during write-intensive operations**: Write-intensive operations, such as log backups or database restores, might experience high disk latency and increased I/O wait times due to misaligned I/O operations, leading to performance bottlenecks and slow response times.
+- **Performance bottlenecks during write-intensive operations**: Write-intensive operations, such as log backups or database restores, might experience high disk latency and increased I/O wait times due to misaligned I/O operations, leading to performance bottlenecks and slow response times.
 
-## Verify sector size 
+## Verify the sector size 
 
 To avoid misaligned I/O operations, it's important to ensure that the physical sector size of the disk drives is consistent across all servers and storage systems.
 
 You can verify the [sector size](../../azure-sql/sql-installation-fails-sector-size-error-azure-vm.md) by running the following command in an elevated command prompt:
 
 ```cmd
-fsutil fsinfo sectorinfo <volume pathname>
+fsutil fsinfo sectorinfo <volume path name>
 ```
 
-The following screenshot shows the output of the `fsutil fsinfo sectorinfo` command for the `E:` drive, which has a sector size of 8 KB, but a physical sector size of 4 KB, causing misaligned I/O operations: 
+The following screenshot shows the output of the `fsutil fsinfo sectorinfo` command for the `E:` drive, which has a sector size of 8 KB but a physical sector size of 4 KB, causing misaligned I/O operations: 
 
-:::image type="content" source="../../azure-sql/media/sql-installation-fails-error-azure-vm/8k-sector-size-example.png" alt-text="Screenshot of command prompt output of 8k sector size.":::
+:::image type="content" source="../../azure-sql/media/sql-installation-fails-error-azure-vm/8k-sector-size-example.png" alt-text="Screenshot of the command prompt output of the 8 KB sector size.":::
 
 ## Resolution 
 
-If you're experiencing performance degradation due to misaligned I/O operations, and you're unable to [modify your sector size](../database-file-operations/troubleshoot-os-4kb-disk-sector-size.md#resolutions), you can use [Trace Flag 1800](/sql/t-sql/database-console-commands/dbcc-traceon-trace-flags-transact-sql#tf1800) as a global startup parameter to force SQL Server to use a consistent 4-KB sector size for transaction log I/O operations.
+If you're experiencing performance degradation due to misaligned I/O operations and can't [modify your sector size](../database-file-operations/troubleshoot-os-4kb-disk-sector-size.md#resolutions), you can use [Trace Flag 1800](/sql/t-sql/database-console-commands/dbcc-traceon-trace-flags-transact-sql#tf1800) as a global startup parameter to force SQL Server to use a consistent 4-KB sector size for transaction log I/O operations.
 
 To enable Trace Flag 1800 as a startup parameter, follow these steps:
 
 1. On the system where SQL Server is installed, open [SQL Server Configuration Manager](/sql/relational-databases/sql-server-configuration-manager). 
-1. Expand **SQL Server Configuration Configuration Manager (Local**) and select **SQL Server Services**. 
+1. Expand **SQL Server Configuration Manager (Local**) and select **SQL Server Services**. 
 1. Right-click the SQL Server instance you want to configure and select **Properties**: 
 
-   :::image type="content" source="media/performance-degradation-misaligned-io-sector-error/sql-server-configuration-manager-properties.png" alt-text="Screenshot of the SQL Server service right-click menu with properties highlighted.":::
+   :::image type="content" source="media/performance-degradation-misaligned-io-sector-error/sql-server-configuration-manager-properties.png" alt-text="Screenshot of the SQL Server service right-click menu with Properties highlighted.":::
 
-1. In **SQL Server properties**, select the **Startup Parameters** tab, enter `-T1800` in the **Specify a startup parameter** field, and select **Add** to add the parameter to the list. 
+1. In **SQL Server Properties**, select the **Startup Parameters** tab, enter `-T1800` in the **Specify a startup parameter** field, and select **Add** to add the parameter to the list. 
 
-   :::image type="content" source="media/performance-degradation-misaligned-io-sector-error/add-1800-trace-flag.png" alt-text="Screenshot of adding the trace flag as a startup parameter in SQL Server properties.":::
+   :::image type="content" source="media/performance-degradation-misaligned-io-sector-error/add-1800-trace-flag.png" alt-text="Screenshot of adding the trace flag as a startup parameter in SQL Server Properties.":::
 
 1. Confirm your trace flag has been added to the list of startup parameters. Select **OK** to save your changes: