SQL error 825 indicates that the read operation had to be reissued at least one time, and indicates a major problem with the disk hardware.

Here at Bobcares, we have seen several such SQL related issues as part of our Server Management Services for web hosts and online service providers.

Today we’ll take a look at the cause for this error and see how to fix it.

More about SQL error 825

The error 825 is also called as the read-retry warning.

This error tells a retry operation was needed. Also, it tells how many times SQL Server had to retry the attempt before it was successful.

This message doesn’t mention that there is a SQL server problem. Instead, it indicates a larger problem with the disk subsystem which may lead to data loss or database corruption if it is not resolved.

Here is a complete error message,

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Msg 825, Level 10, State 2, Line 1.
A read of the file ‘D:\SQLskills\TestReadRetry.mdf’ at offset 0×0000017653C000 succeeded after failing 2 time(s) with error: incorrect checksum (expected: 0×4a224f20; actual: 0×2216ee12). Additional messages in the SQL Server error log and system event log may provide more detail. This error condition threatens database integrity and must be corrected. Complete a full database consistency check (DBCC CHECKDB). This error can be caused by many factors; for more information, see SQL Server Books Online.
~~

How we resolve SQL error 825

Here are some suggestions our Support Engineers provide to our customers to resolve this error message.

1. Check the error log to find clues that explain the problem.

2. This error mainly relates to disk, the disk controllers, array cards, or disk drivers. So make sure to check the disk system.

3. Contact the disk manufacturer for the latest utilities for checking the status of your disk system. Also, check for the latest driver updates.

4. Try moving all files into a new physical drive(on a new hardware LUN). Below are the steps for the same.

• First, add a new Drive (for example, X)
• Secondly, create the same folder structure as on the D drive.
• Then stop the SQL Service.
• Now move files from D drive to X drive.
• Swap the Drive letters (D > Y, X > D, Y > X)
• Finally, start the SQL Service. (you might get some permission errors so make sure to set permissions accordingly)

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Conclusion

In short, this SQL error indicates a major disk problem and not a SQL server problem. Today, we saw how our Support Engineers fix this SQL error.