Wait Type PREEMPTIVE_OS_DEVICEIOCONTROL

Wait statistics, in the context of SQL Server, refer to the amount of time that a query spends waiting to access data in the database. When a client application requests data from the database, the request is placed in a queue and the client application must wait for its turn to access the data. The time that the query spends waiting is called a "wait" and is tracked by SQL Server. This information can be used to identify potential performance bottlenecks and optimize the performance of the database. Wait statistics are commonly used by database administrators to diagnose and troubleshoot performance issues in SQL Server.

When working with SQL Server, understanding wait types is crucial for diagnosing performance issues. One such wait type that can appear in your system is PREEMPTIVE_OS_DEVICEIOCONTROL. In this blog post, we’ll break it down in simple terms and explain how to monitor it effectively.

What is PREEMPTIVE_OS_DEVICEIOCONTROL?

The PREEMPTIVE_OS_DEVICEIOCONTROL wait type occurs when SQL Server makes a call to the underlying operating system to handle I/O-related operations. These could involve communicating with storage devices, such as hard drives or SSDs, through operating system APIs.

This is a preemptive wait, meaning SQL Server steps aside to let the OS handle the request. While this happens, SQL Server’s thread is waiting for the OS to complete the task. Unlike cooperative waits, preemptive waits occur outside the control of SQL Server’s scheduling mechanisms.

When Does This Wait Type Happen?

The PREEMPTIVE_OS_DEVICEIOCONTROL wait type can surface in scenarios like:

• Accessing external storage devices with high latency.
• Performing backup or restore operations.
• Running queries that involve significant I/O activity.
• Interacting with third-party drivers or hardware APIs.

While occasional occurrences are normal, a high prevalence of this wait type could indicate issues with storage or I/O performance that require investigation.

How to Monitor PREEMPTIVE_OS_DEVICEIOCONTROL Waits

To keep track of wait types like PREEMPTIVE_OS_DEVICEIOCONTROL, monitoring is essential. One powerful tool for this is Database Health Monitor. Its Historic Waits Monitoring feature allows you to identify trends in wait types over time, making it easier to spot anomalies and recurring issues.

With Database Health Monitor, you can:

• View historical wait type trends to pinpoint when issues started.
• Analyze which queries or operations are contributing to the wait.
• Correlate wait types with system activity for better troubleshooting.

What Can You Do to Reduce These Waits?

If PREEMPTIVE_OS_DEVICEIOCONTROL waits are affecting your SQL Server’s performance, consider the following actions:

• Examine your storage subsystem for latency or bottlenecks.
• Verify the health and configuration of your drives and drivers.
• Optimize backup and restore operations by scheduling them during low activity periods.
• Ensure third-party drivers and firmware are up-to-date and compatible with your SQL Server version.

Monitor Waits with Confidence

To stay on top of your SQL Server’s performance, having the right tools makes all the difference. Database Health Monitor is designed to provide deep insights into SQL Server waits, helping you identify and address issues quickly. Whether it’s PREEMPTIVE_OS_DEVICEIOCONTROL or other wait types, Database Health Monitor empowers you to maintain a smooth-running system.

Download Database Health Monitor today to take control of your SQL Server performance!

Watch on YouTube

Find out more about our SQL Server Managed Services

Applies to

• SQL Server 2019
• SQL Server 2022

Related Waits

See Also

• More About PREEMPTIVE_OS_DEVICEIOCONTROL