As a SQL Server user, you may have come across situations where you need to manage and allocate resources efficiently. SQL Server Resource Governor is a powerful feature that allows you to do just that. In this article, we will explore the concept of Resource Governor and its various capabilities.

Resource Governor is a feature introduced in SQL Server 2008 that enables you to manage and allocate resources such as CPU and memory among different workloads or applications running on the same SQL Server instance. It provides a way to prioritize and control the resource usage based on predefined rules and policies.

One of the enhancements introduced in SQL Server 2012 is the allocation of resources. Let’s understand this with some examples:

Example 1: Single Workload

Suppose you have a server with only a Reporting Workload. You have configured the Resource Governor with a maximum CPU usage of 30% for this workload. In this scenario, SQL Server will not limit the CPU usage to only 30%. It will utilize all available CPU resources if needed, exceeding the specified limit.

Example 2: Multiple Workloads

Now, let’s consider a situation where you have both a Reporting Workload and a heavy Application/OLTP workload. In this case, SQL Server will allocate a maximum of 30% CPU resources to the Reporting Workload and allocate the remaining resources to the heavy Application/OLTP workload. This allocation ensures better utilization of resources and optimized performance.

Example 3: Enforcing Maximum CPU Workload

There may be scenarios where you want to enforce a maximum CPU workload, regardless of the other workloads and the enhanced allocation algorithm. This is where the keyword CAP_CPU_PERCENT comes into play. By specifying CAP_CPU_PERCENT, you can set a hard cap on the CPU bandwidth that all requests in the resource pool will receive.

For example, if you want to create a resource pool for a Report Server with a maximum CPU usage of 30% but want to enforce a hard cap of 40%, you can use the following code:

CREATE RESOURCE POOL ReportServerPool
WITH
( MIN_CPU_PERCENT=0,
MAX_CPU_PERCENT=30,
CAP_CPU_PERCENT=40,
MIN_MEMORY_PERCENT=0,
MAX_MEMORY_PERCENT=30)

In this case, the SQL Server instance will use the maximum CPU at 30% when under heavy load with different workloads. However, when the SQL Server instance is not under workload, it may exceed the 30% limit. However, the CAP_CPU_PERCENT setting ensures that it will not go over 40% in any case, effectively limiting the CPU usage.

SQL Server Resource Governor is a powerful tool that allows you to manage and allocate resources efficiently. By understanding its capabilities and using features like CAP_CPU_PERCENT, you can optimize the performance of your SQL Server instance and ensure fair resource allocation among different workloads.

Thank you for reading this article. If you have any questions or suggestions, feel free to leave a comment below.