Multi-Server Administration : Policy-Based Management

Policy-Based Management is a new feature in SQL Server 2008 that allows you to define and implement policies across the organization. Policy-Based Management was initially called the Declarative Management Framework but was changed before the final release of SQL Server 2008. First, we will show you how to manually create a policy and then move on to some of the more automated ways of creating a policy.

There are a few key terms you should be familiar with when discussing Policy-Based Management:

• Target: Object that is being managed by a policy

• Facet: Group of logical properties that can be applied to a target

• Condition: A check that is evaluated by a policy

• Policy: A condition that is applied to a given set of objects

• Category: Group of policies that help you manage policy enforcement

When you look at the Policy Management node in SQL Server Management Studio, you see three folders: Policies, Conditions, and Facets. The folder structure forms a sort of hierarchy of the objects required to use Policy-Based Management. Facets are required in order to create conditions, and conditions are required in order to create policies.

1. Manually Creating a Policy

To manually create a policy you must first create a condition, and then you will be able to create a policy that uses that condition. Once you have created a policy, you can then place it in the appropriate category and apply it to one or more targets.

Let's start by creating a condition that will be used in a policy. In this example, we will create a condition that checks to see if a database is using the full recovery model. To create a new condition, right-click the Conditions folder and select New Condition. (The Conditions folder is located under Policy Management in the Management node of the Object Explorer in SQL Server Management Studio.) This will bring you to the Create New Condition dialog box, as shown in Figure 1.

Figure 1. Policy-Based Management Create New Condition dialog box

Create the new condition by entering the following information:

• Name: In the Name field, enter Full Recovery Model. Notice that the dialog box title now says "Create New Condition – Full Recovery Model," and the error displayed under the title bar changes from saying that the name is not set to saying that the ExpressionNode is not set.

• Facet: Before you set the expression, change the Facet field to Database Maintenance by selecting it from the drop-down list.

• Expression: Click the cell in the Field column and select @RecoveryModel from the drop-down list. Leave the equals sign (=) in the Operator column. You can see all the available operators by clicking on the drop-down list. Click the drop-down list in the Value column and select Full. Notice that the Value column changes to reflect the values that are appropriate for the attribute that has been selected in the Field column. For example, if you change the field to @LastBackupDate, a calendar control would be displayed in the Value drop-down list. You can also enter multiple expressions using AND/OR logic by selecting the next row and entering the appropriate information.

• Description: Optionally you can enter a description by selecting the Description page on the left and entering it in the text box provided. Select the Description page and type a brief description, such as Condition to check to make sure a database recovery model is set to Full.

Once you've entered all the information correctly, the errors are removed from the top of the dialog box, and the status changes to Ready as shown in Figure 2.

Figure 2. Completed Policy-Based Management Create New Condition dialog box

Click OK to finish creating the condition. You should now see the new condition under the Conditions folder in Policy-Based Management.

Now that you have created a condition, you are ready to create a policy that can use the condition. To create a new policy, right-click the Policies folder and select New Policy. (The Policies folder is located under Policy Management in the Management node of the Object Explorer in SQL Server Management Studio.) This will bring you to the Create New Policy dialog box as shown in Figure 3.

Figure 3. Policy-Based Management Create New Policy dialog box

Create the new policy by entering the following information:

• Name: In the Name field enter Full Database Recovery Model. Notice the title now says "Create New Policy – Full Database Recovery Model," and the error displayed now states that the Condition is not set instead of the Name.

• Check Condition: Set the Check Condition option by clicking the drop-down list and selecting Full Recovery Model. If this is your first time using Policy-Based Management, it should be the only thing in the drop-down you are allowed to select. Once the condition has been selected, you can click the ellipsis next to the drop-down list to edit or review the condition directly from the policy.

• Against Targets: Once the condition has been set, the target is automatically set to Every Database. You can exclude databases by clicking the drop-down menu next to Every and selecting New Condition (see the completed policy later in Figure 7-5). This will allow you to create a condition you can use to exclude certain databases based on given properties exposed in the database facet. For example, you may want to create a condition that will exclude read-only databases from a policy that verifies all databases are using the full recovery model.

• Evaluation Mode: Use this drop-down list to select the evaluation mode. For this example, we will be using On Demand. Selecting On Schedule will enable you to either assign an existing schedule to run the policy or create a new one. Also, selecting On Schedule will allow you to enable the policy by selecting the Enabled check box located directly under the policy name. Only enabled policies will be run by the scheduled job that will be created to check the policies. Valid evaluation modes are On Demand, On Change: Prevent, On Change: Log Only, and On Schedule. The evaluation modes displayed in the drop-down list depend on the facet you are using in the condition. All facets support On Change and On Schedule, but On Change: Prevent relies on the facet being able to use Data Definition Language (DDL) triggers to roll back the transaction. On Change: Log Only relies on the ability of the facet change to be captured by an event.

• Server Restriction: You can create a condition to exclude servers from the policy by using the server facet. For example, you could create a condition that only evaluates the policy on SQL Servers that are running the Enterprise or Standard Edition. For this example, we will not be using a server restriction.

Select the Description page, as shown in Figure 4, to configure the remaining options.

Figure 4. Create New Policy dialog box Description page

The remaining options in Figure 4 are as follows:

• Category: For this example, we will leave the category set to Default. To change the category, you would click the drop-down menu and select a defined category or click the New button to create a new category. We will show you how to manage categories later in this section.

• Description: Optionally, you can define a description by entering it in the text box provided. Enter a brief description, such as Policy to make sure a database recovery model is set to Full.

• Text to Display: Type the text that will be displayed as a hyperlink when the policy has been violated. For this example, type something such as Choosing a Recovery Model.

• Address: Type the address for the hyperlink. This could be a hyperlink to MSDN explaining why you should use the policy or even to an internal web site that lists the standards for the organization. For this example, type http://msdn.microsoft.com/en-us/library/ms175987.aspx, which will take you to an article on MSDN about choosing a recovery model. Click the Test Link button to open a browser and validate the link.

Once you have entered all of the information correctly, the errors are removed from the top of the dialog box, and the status changes to Ready. The completed policy is shown in Figure 5.

Figure 5. Completed Policy-Based Management Create New Policy dialog box

Click OK to finish creating the policy. You should now see the new policy under the Policies folder in Policy-Based Management.

Now that you have created a policy, you are ready to evaluate that policy against the targets. Right-click the policy you just created named Full Database Recovery Model and select Evaluate from the context menu. The policy will be evaluated against the defined targets, and the Evaluate Policies dialog box will be displayed as shown in Figure 6. Notice that one of my targets did not comply with the policy and is displayed with a red X, indicating the failure.

Figure 6. Evaluate Policies dialog box

Click on the View hyperlink in the Target Details column to display comprehensive information about why the policy failed. After clicking the View hyperlink, you will be able to see the Results Detailed View dialog box, as shown in Figure 7. The Results Detailed View will not only show you the expected value for the condition that was used, you will also be able to see the actual value to determine why the condition failed. You will also see the description you entered for the policy, along with the hyperlink information you defined when creating the policy. Close the Results Detailed View dialog and return to the Evaluate Policies dialog box.

Figure 7. Results Detailed View dialog box

Policy-Based Management allows you to fix certain violations by checking boxes next to messages indicating noncompliance in the Evaluate Policies dialog box and selecting Apply. Not all policies can be automatically corrected. For example, there is a predefined policy that you must manually address stating that data and log files for a given database cannot be located on the same drive. There are too many variables involved in moving data files for SQL Server to automatically move them for you. You will know that you cannot automatically correct a policy failure if there is no check box that will allow you to select the policy in violation.

If you have selected policy violations that you wish to automatically correct, then click the Apply button. Your result will be a confirmation box, as shown in Figure 8, warning you that all noncompliant selected targets will be modified. Select Yes to accept and apply the changes.

Figure 8. Policy Evaluation Warning message box

To manage policy categories, right-click on Policy Management in the SQL Server Management Studio Object Explorer and select Manage Categories from the context menu. This will display the Manage Policy Categories dialog box, shown in Figure 7-9. Here you can add categories and specify whether the database subscriptions to a category will be mandated. If a category is mandated, it will be evaluated against all targets; if not you will have to specifically designate the targets that will be evaluated. All policies must be assigned to a category, and if no category is specifically chosen, the policy will be assigned to the Default category. One thing to note about the Default category is that you cannot remove the Mandate Database Subscriptions check box. All policies that remain in the Default category will be mandated against all targets.

Figure 9. Manage Policy Categories dialog box

That's all there is to manually creating and executing a policy. Since Microsoft provides predefined policies, you may never have to manually create a policy, but it is the best way to become familiar with the available options. One other thing that should be noted is that policies are stored in the msdb database, so once you have created a new policy, you should make sure the msdb is backed up.

2. Exporting Current State As Policy

Many policies can be exported based on the current state of a facet. Once you have configured the facet, you can export the current state of the facet as a policy. This section will walk you through exporting a Surface Area Configuration policy using the current state.

If you are familiar with SQL Server 2005, you may have noticed that the Surface Area Configuration tool is not available when you install SQL Server 2008. The configuration of the Database Engine features are now managed using the Surface Area Configuration facet in Policy-Based Management. In SQL Server Management Studio, right-click on the server instance you would like to configure and select Facets from the context menu. This will bring up the View Facets dialog box. Change the Facet option to Surface Area Configuration, as shown in Figure 10.

Figure 10. The View Facets dialog box displays available facets for an object.

From the View Facets dialog, you can configure the values and select OK to apply the new configurations. You can also export the current configurations as a policy to the local server or to a file that you can import and apply to multiple servers across the organization. Click on the Export Current State as Policy button on the View Facets dialog box to bring up the Export as Policy dialog box, shown in Figure 11.

Figure 11. Export as Policy dialog box

The Export as Policy dialog box allows you to name the policy and condition that will be created. By default, the policy and condition name will be FacetName_YYYYMMDD. For this demonstration, save the policy to the local server and click OK. Click OK again to close the View Facets dialog box.

You should now be able to see the new policy and condition that was created in the Policy Management node in SQL Server Management Studio. You can manage and evaluate the policy using the same methods as if you created it manually. You can use other objects to export current state as policy as well. For example, if you right-click on a database and select Facets, it will bring up the View Facets dialog box with a drop-down list of available facets for the database object.

3. Importing a Predefined Policy

We mentioned earlier that you could import predefined policies provided by Microsoft that correspond with Best Practice Analyzer rules and default settings in the Surface Area Configuration tool. Microsoft provides these policies in the form of XML files as a part of the normal installation process. The XML files are located in the Polices folder in the Tools directory where you installed SQL Server. Importing a predefined policy is nice because it not only creates the policy, but all the conditions required as well. You also know that the policy is based on Microsoft best practices and has been tested by someone other than yourself. You may also want to create your own custom policies and deploy them as well. This section will walk you through the steps required to import a policy.

For this example, we will be importing a policy that checks to make sure the data and log files are not stored on the same drive. Right-click on the Policies folder located under the Policy Management node in SQL Server Management Studio, and then select Import Policy from the context menu. This will open the Import dialog box, as shown in Figure 12.

Figure 12. Import dialog box

From the Files to Import field, click the ellipsis to navigate to the C:\Program Files\Microsoft SQL Server\100\Tools\Policies\DatabaseEngine\1033\ directory and select the Data and Log File Location.xml file. (If you made custom installation changes, your files may be in a different directory). Select the Replace Duplicates with Items Imported check box to overwrite any policies and conditions that have the same name of the policy you are importing. You can choose to preserve the state of the policy being imported, enable the policy on import, or, disable the policy on import. For this example, select Preserve Policy State on Import and select OK to import the policy.

You can now see the new policy and the conditions that were created under the Policy Management node in SQL Server Management Studio. The new policy is called Data and Log File Location (see Figure 13). The policy uses two conditions: one that checks to make sure the files are on separate logical drives (called Data and Log Files on Separate Drives), and one that places a server restriction on the policy (called Enterprise or Standard Edition). As you can see in Figure 13, you can use a condition as a check condition or a server restriction. By placing a server restriction on the policy, it will only be evaluated against servers that meet the condition defined for the restriction.

Figure 13. Data and Log File Location Policy General Tab

As you can see, importing a predefined policy is an easy way to make sure your servers are using Microsoft best practices or standards that you have implemented within your organization. You can see the final policy in Figures 13 and 14. Figure 13 shows the general options that were automatically created when you imported the policy.

All the category, description, and hyperlink information is also prepopulated with the policy, as shown in Figure 14, making it easy to reference the documentation as to why this policy should be implemented.

Figure 14. Data and Log File Location Policy Description Tab