SQL Server Wait Type: PREEMPTIVE_OS_MOVEFILE

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.

SQL Server has many different types of wait types that can occur when running a query. The PREEMPTIVE_OS_MOVEFILE wait type is one of them, and it can be a bit tricky to understand. Lets explain what PREEMPTIVE_OS_MOVEFILE wait types are and why they occur in SQL Server.

First, its important to understand what wait types are in general. In SQL Server, a wait type is a state in which a task is waiting for something to happen before it can continue executing. For example, a task might be waiting for a lock to be released, or for data to be returned from a disk. When a task is in a wait state, it is not using any CPU resources, and it is essentially idle until the thing it is waiting for happens.

The PREEMPTIVE_OS_MOVEFILE wait type specifically occurs when a task is waiting for the operating system to move a file from one location to another. This might happen for a number of reasons, such as when a database is being backed up, or when a large amount of data is being imported or exported.

One thing to note about PREEMPTIVE_OS_MOVEFILE wait types is that they are “preemptive” waits. This means that they are executed by the operating system outside of the normal SQL Server execution context. In other words, the SQL Server query engine is not directly responsible for these waits – they are being handled by the operating system.

If you are seeing a lot of PREEMPTIVE_OS_MOVEFILE wait types in your SQL Server instance, it might indicate that you are performing a lot of file operations, such as backups or imports/exports. This can sometimes cause performance issues, as these operations can be resource-intensive. If you are experiencing performance issues related to PREEMPTIVE_OS_MOVEFILE wait types, you might want to consider optimizing your file operations, or using faster storage devices (such as solid-state drives) for storing your databases.

In summary, PREEMPTIVE_OS_MOVEFILE wait types occur when a task in SQL Server is waiting for the operating system to move a file from one location to another. These wait types can be caused by a variety of file operations, and can sometimes lead to performance issues. If you are seeing a lot of PREEMPTIVE_OS_MOVEFILE wait types in your SQL Server instance, you might want to consider optimizing your file operations to improve performance.

More details avilable on this wait type here: http://DatabaseHealth.com/Waits/PREEMPTIVE_OS_MOVEFILE.html

Do you have a favorite tool for monitoring your wait statistics on SQL Server over time? This is something that you can use Database Health monitor to do. More details at http://DatabaseHealth.com.

If you are having performance issues associated with this wait type and need some help, please contact us with our 30 minute consultation link.