Data Monitoring / SQL Server Availability & Capacity
SQL Server: Login failure patterns
Authentication failures increase after a service account rotation. Group error evidence by account, client and first occurrence while protecting credentials.
Environment and inputs: SQL Server operational monitoring; availability groups, SQL Agent and host-level metrics depend on edition, service and deployment.
Failure scenario
Authentication failures increase after a service account rotation. Confirm the cause before choosing a fix.
Evidence to collect
Group error evidence by account, client and first occurrence while protecting credentials. Record the time, affected scope and a healthy comparison interval.
Fix the confirmed cause
Correct the affected service configuration and distinguish expected retries from unauthorized attempts. Write the expected result first. Change one relevant setting at a time.
Check the result and hand over
Repeat the check for login failure patterns using the same scope and a representative interval. Check that the symptom is resolved, expected records are present and downstream results are correct. If coverage, correctness or latency worsens, restore the recorded configuration through the agreed rollback process.
Scope and precautions
Prefer read-only access and limit queries to the relevant period or dataset. This example has not been tested on your systems. Test changes in an approved environment. Keep credentials and sensitive data out of shared evidence.