Hướng dẫn học Microsoft SQL Server 2008 part 105 ppsx

Nielsen c42.tex V4 - 07/21/2009 2:25pm Page 1002 Part VI Enterprise Data Management ■ DBCC dllname FREE): Unloads the specified dll from memory ■ DBCC MEMORYSTATUS: Provides a snapshot of the current memory status of SQL Server. This command is very useful in troubleshooting issues that relate to SQL Server memory consumption. ■ DBCC USEROPTIONS: Returns the active SET options for the current connections The following three DBCC commands are used with trace flags. Trace flags are used temporarily to set certain specific SQL Server characteristics or turn off some behavior. For example, trace flag 1204 is used to enabled deadlock reporting to SQL Server ErrorLog. ■ DBCC TRACEON: Turns on the specified trace flags ■ DBCC TRACEOFF: Turns off the specified trace flags ■ DBCC TRACESTATUS: Displays the active trace flags Managing Database Maintenance SQL Server provides a host of database maintenance commands. Fortunately, it also provides the DBA with ways to schedule maintenance tasks. Planning database maintenance Database maintenance plans include the following routine tasks: ■ Checking database integrity ■ Performing index maintenance ■ Updating database statistics ■ Performing database backups ■ Shrinking the database ■ Checking file sizes and free disk space These maintenance tasks can be automated and scheduled using the SQL Server Agent service. The maintenance tasks are referred to a s SQL Server Agent jobs. Maintenance plan There are two ways to create a maintenance plan: ■ Maintenance Plan Wizard: Used to quickly create a basic maintenance plan, this wizard enables you to choose typical predefined maintenance tasks such as performing database backup, rebuilding indexes, updating statistics, checking data integrity, and shrinking the database. It does not allow you to add any custom tasks. ■ Maintenance Plan Design Surface: Used for designing maintenance plans with more flexi- bility, this option enables you to create a workflow of typical maintenance tasks and custom maintenance tasks using T-SQL scripts. It also allows extended logging, which can be very useful for troubleshooting purposes. All of the maintenance plans appear in the Management\Maintenance Plans folder of SQL Server Management Studio. To launch the Maintenance Plan Wizard, right-click the Maintenance Plans 1002 www.getcoolebook.com Nielsen c42.tex V4 - 07/21/2009 2:25pm Page 1003 Maintaining the Database 42 folder and choose Maintenance Plan Wizard. Follow the simple step-by-step wizard to create the maintenance plan. To launch the Maintenance Plan Design Surface, right-click the Maintenance Plans folder and choose New Maintenance Plan from the context menu. Type a name for the maintenance plan in the New Maintenance Plan dialog and click OK. Once you assign a name to your maintenance plan, Management Studio o pens a new window that includes the maintenance plan name, a description, the time you want to schedule the maintenance plan, and a list of tasks to perform. Figure 42-1 shows a sample maintenance plan with some tasks already entered. Adding a task A maintenance plan must contain at least one task. Fortunately, it isn’t difficult to add one. Simply drag and drop the appropriate task from the Toolbox, shown in Figure 42-2, to the design area of the main- tenance plan. The resulting task will appear as a square (refer to Figure 42-1). FIGURE 42-1 Create a maintenance plan by adding some tasks and scheduling a time to perform the tasks. 1003 www.getcoolebook.com Nielsen c42.tex V4 - 07/21/2009 2:25pm Page 1004 Part VI Enterprise Data Management FIGURE 42-2 Use the Toolbox to add new tasks to your maintenance plan. FIGURE 42-3 Define the task specifics using the Properties window. 1004 www.getcoolebook.com Nielsen c42.tex V4 - 07/21/2009 2:25pm Page 1005 Maintaining the Database 42 The task isn’t configured yet. Use the Properties window, shown in Figure 42-3, to configure the task. The content of the Properties window varies by task. For example, when you select Back Up Database Task, you’ll see properties for choosing the kind of database, the backup device type, and other infor- mation associated with backing up the database. The upper portion of the Properties window contains the name of the selected task. You can choose other tasks using the drop-down list box. The middle of the Properties window contains a list of properties for the selected task. You can organize the proper- ties by category or in alphabetical order. The lower part of the Properties window contains a description for the selected property. Once you have worked with tasks f or a while, the description usually provides enough information to help you remember how to use the selected property. Sometimes you may not want to use the Properties window. For e xample, you might be working with a new task. In this case, you can bypass the Properties window by double-clicking the task. A task-specific window like the one shown in Figure 42-4 for a backup task will appear. Unlike the Properties window, this dialog displays the task properties in context. In addition, it grays out task elements until you define the correct functionality. For example, when you choose to back up specific databases, the dialog won’t let you perform any other configuration task until you choose one or more databases for the backup. FIGURE 42-4 In addition to the Properties window, you can use the task-related dialog for configuration. 1005 www.getcoolebook.com Nielsen c42.tex V4 - 07/21/2009 2:25pm Page 1006 Part VI Enterprise Data Management It’s interesting to click View T-SQL when you finish configuring the task. The resulting window, like the one shown in Figure 42-5, displays the T-SQL that the task will use. The Transact SQL (Task Gener- ated) window won’t let you edit the command, but seeing how the Maintenance Plan Wizard generates the code can prove helpful when you need to create T-SQL commands of your own. FIGURE 42-5 The View T-SQL button enables you to see the Transact SQL command. You know when a task is complete by the appearance of the square in the design area. Incomplete tasks, those that won’t execute correctly, display a red circle with an X through it on the right side of the window. After you define a task, add the next task in your list. You can add the tasks in any order and place them in any order onscreen. Connect the tasks in the order in which you want SQL Server to exe- cute them. Figure 42-1 showed two tasks, with one task connected to the next task in the list. In that example, first the integrity of the AdventureWorks2008 database is checked, and then it is backed up. Defining the schedule You can perform tasks on demand or schedule them to run automatically. Generally, it’s a good idea to set standard tasks such as backup to run automatically. Click the ellipses next to the Schedule field to display the Job Schedule Properties dialog, shown in Figure 42-6, when you want to change the task schedule. Select the scheduling requirements for the task. For example, you can set a task to run daily, weekly, or monthly. The dialog also enables you to select a specific starting time for the task and determine when the scheduling begins and ends. The one form of scheduling that this dialog doesn’t provide is on demand. To set the maintenance task to run on demand, simply leave the Job Schedule Properties empty. 1006 www.getcoolebook.com Nielsen c42.tex V4 - 07/21/2009 2:25pm Page 1007 Maintaining the Database 42 FIGURE 42-6 Define a schedule that meets the task requirements; use off-hours scheduling for resource-intensive tasks. Creating new connections Depending on your database setup, you might need to create multiple connections to perform a particular task. The maintenance plan always provides a connection to the default instance of the local database. Click Manage Connections to add more connections to the current maintenance plan (any additions won’t affect other maintenance plans you create). The Manage Connections dialog shown in Figure 42-7 will appear. Click Add in the Manage Connections dialog to add a new connection. The New Connection dialog will appear. A connection consists of three elements: connection name, server name, and server security. Choose a connection name that reflects the server and instance. Using a name such as ‘‘My Connection’’ won’t be particularly helpful when you need to troubleshoot the maintenance task later. You can either type the server and instance name or select it from a list that the maintenance plan provides when you click the ellipses next to the Select or Enter a Server Name field. Finally, choose between Windows integrated or SQL Server security. Click OK to add the new connection to the list. 1007 www.getcoolebook.com Nielsen c42.tex V4 - 07/21/2009 2:25pm Page 1008 Part VI Enterprise Data Management FIGURE 42-7 Add new connections as needed to perform maintenance tasks. The Manage Connections dialog also enables you to edit existing connections or remove old connections. When you edit an existing connection, you see a New Connection dialog in which you can change the logon arguments or the server name for the connection. The dialog grays out the other fields. Simply click Remove to delete a connection you no longer need from the list. Connection deletion is a one-way process, and it happens quite quickly. Make sure you have the correct connection selected before you click Remove because the maintenance plan won’t ask for confirmation before deleting the connection. Logging the maintenance progress Many of the maintenance tasks that you automate will execute during off hours, when you’re unlikely to be around to monitor the system. Fortunately, you can set maintenance tasks to log and r eport their actions so that you don’t need to watch them every moment. T o use this feature, click the Reporting and Logging icon next to the Manage Connections icon. The Reporting and Logging dialog shown in Figure 42-8 will appear. The Reporting and Logging dialog includes an option that enables you to send the report to a file or your e-mail. The e-mail feature is quite handy and saves you the time of searching for the file on the hard drive. Conversely, the text file provides an archive that could prove helpful long after you’ve deleted the e-mail from your inbox. Once you configure the reporting options, click OK, and the maintenance plan will record its actions for you. Best Practice Y ou normally want to provide extended information about all maintenance tasks that the system performs without your supervision. Even the smallest piece of information can help you determine where a particular maintenance action went awry. 1008 www.getcoolebook.com Nielsen c42.tex V4 - 07/21/2009 2:25pm Page 1009 Maintaining the Database 42 FIGURE 42-8 Use the Reporting and Logging dialog to monitor your maintenance tasks. Command-line maintenance Database maintenance is normally performed within SQL Server Management Studio or automated with SQL Server Agent, but maintenance can be performed from the DOS command prompt by means of the SQLMaint utility. This utility has numerous options that can perform backups, update statistics, and run DBCC. This feature will be removed in the next version of SQL Server. Do not use this feature in new development work, and plan to change applications that use this feature. To run SQL Server maintenance plans from the command line, use the dtexec utility. Specific information on SQLMaint and dtexec can be found in SQL Server 2008 Books Online. Monitoring database maintenance It’s not enough to simply schedule tasks; they must be monitored as well. In larger installations with dozens of SQL Servers spread around the globe, monitoring the health of SQL Server and the databases 1009 www.getcoolebook.com Nielsen c42.tex V4 - 07/21/2009 2:25pm Page 1010 Part VI Enterprise Data Management is itself a full-time job. Table 42-1 provides a sample DBA daily checklist that can be used as a starting point for developing a database monitoring plan. TABLE 42-1 DBA Daily Checklist Item S M T W T F S System Databases Backup Production User Databases Backup SQL Agent, SQL Maint, & DTC Running Database Size, Growth, Disk Free Space Batch Jobs Execute OK DBCC Jobs Execute OK SQL Log Errors Replication Log Agent Running Replication Distribution Cleanup Job Execute OK SQL Server Last Reboot Depending on the number of servers and the complexity, the DBA daily checklist can be maintained manually with an Excel spreadsheet or tracked in a SQL Server table. Summary This chapter covered database maintenance in detail. SQL Server offers a rich set of commands and utilities that can be used to monitor the health of, and perform maintenance on, SQL Server. The Maintenance Plan Wizard is also available to streamline database maintenance. All installations of SQL Server should also include a database maintenance schedule to assist the DBA in keeping track of maintenance performed. The next chapter explains how to use SQL Server Agent, which may be used to schedule jobs and create custom maintenance jobs, and SQL Server Data base Mail, for sending e-mail from SQL Server. 1010 www.getcoolebook.com Nielsen c43.tex V4 - 07/21/2009 2:32pm Page 1011 Automating Database Maintenance with SQL Server Agent IN THIS CHAPTER Setting up SQL Server Agent Understanding alerts, operators, and jobs Managing alerts Managing operators Managing jobs Setting up Database Mail T he automation of database maintenance is crucial to ensuring that a database is regularly checked, maintained, and optimized. Automated checking consists of monitoring database size to identify issues before they generate mayhem; maintenance includes frequent backups; and optimization involves tweaking the index configuration for optimal performance. Automation ensures that these activities do not consume too much of your time, so you can focus on more pressing issues (such as improving your golf game, perhaps). Ideally, SQL Server can monitor itself and send alerts when it encounters a crit- ical condition. Luckily Microsoft grants this specific wish, because SQL Server includes a powerful component that can send alerts when specific critical condi- tions occur. Better still, this same component also enables the scheduling of rou- tine maintenance tasks either on a one-time basis or on a recurring basis — for example, once a month or, say, on the first Saturday of every month. SQL Server Agent is the service responsible for processing alerts and running scheduled jobs. SQL Server Agent service is not available in SQL Server Express Edition, for which scheduling of jobs has to be done using Windows Scheduler. For more information on Windows Scheduler, search the web, using your preferred search engine or consult Microsoft Windows documentation. Setting Up SQL Server Agent Setting up SQL Server Agent is straightforward, as long as you avoid two pitfalls: The first is rather elementary (a startup issue); the second (a security issue) is a bit more subtle. It makes sense to start with the easy one. Because SQL Server Agent is a Windows service, make sure that the service is restarted if anybody reboots the server. (Microsoft sets this service not to start by default when you 1011 www.getcoolebook.com . jobs, and SQL Server Data base Mail, for sending e-mail from SQL Server. 1010 www.getcoolebook.com Nielsen c43.tex V4 - 07/21/2009 2:32pm Page 1011 Automating Database Maintenance with SQL Server. Saturday of every month. SQL Server Agent is the service responsible for processing alerts and running scheduled jobs. SQL Server Agent service is not available in SQL Server Express Edition,. Execute OK SQL Server Last Reboot Depending on the number of servers and the complexity, the DBA daily checklist can be maintained manually with an Excel spreadsheet or tracked in a SQL Server table. Summary This