Feb 25, 2019 · Microsoft recommends enabling trace flag 1800 to overcome this issue. We can enable trace flag 1800 using DBCC TRACEON and this change will take immediate effect. After you enable the trace you will see below message in the error log. DBCC TRACEON 1800, server process ID (SPID) XXX. This is an informational message.

Jul 11, 2022 · The error message is generated when SQL Server has detected that Log Entries have been written assuming a Sector Size different to the Sector Size found on the current SQL Server instance. This can happen in scenarios such as the below:

Apr 15, 2025 · If you're experiencing performance degradation due to misaligned I/O operations and can't modify your sector size, you can use Trace Flag 1800 as a global startup parameter to force SQL Server to use a consistent 4-KB sector size for transaction log I/O operations.

Jul 8, 2019 · There have been 27888384 misaligned log IOs which required falling back to synchronous IO. What this hints at is a difference in the sector size between the disks on the primary and those on the secondary server (our new SAN).

Jul 28, 2022 · The error message listed in the error log you posted is described in 'Scenario #2' in the article. 2021-11-05 23:42:47.14 spid9s There have been 256 misaligned log IOs which required falling back to synchronous IO.

Jan 4, 2023 · If you’ve run into an issue with LocalDB or SQL Server where the process fails to start and you see an error message about misaligned log IOs, you’re not alone. This issue can be particularly frustrating, especially if you’re not sure where to start in terms of troubleshooting.

Oct 4, 2024 · There have been 256 misaligned log IOs which required falling back to synchronous IO. The current IO is on file C:\Users\galen\AppData\Local\Microsoft\Microsoft SQL Server Local DB\Instances\mssqllocaldb\master.mdf.

Jun 2, 2020 · To "fix" it, you will need to migrate all of the SQL instances in the AG to have the same block size. If it is NOT part of an AG, then I'd be curious to know when the error is being thrown. Is it...

Aug 7, 2019 · While restoring a log on a secondary replica to prepare a database for joining an availability group I suddenly received a flurry of 'There have been n misaligned log IOs which required...

Nov 30, 2015 · This blog post shows how to address the problem by modifying the sector size - Message misaligned log IOs which required falling back to synchronous IO in SQL Server Error Log; Its always a best practice to have same hardware configuration on primary and secondary servers - Disk, CPU, RAM, etc.