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Instant Answer A major improvement in Windows XP is the existence of a command-line equivalent to the graphical Disk Defragmenter console, and that's DEFRAG.EXE. The -a qualifier does an analysis, and the -f qualifier forces a defrag even if the utility doesn't think you need it. You can now run defrag operations via batch files, scripts, and the Scheduled Tasks tool - which brings us to the next section.
Disk maintenance and Scheduled Tasks
If remembering to defragment your disks once in a while is helpful, having Windows XP automatically defragment them on a regular basis is more helpful. This is as good a time as any to introduce the Scheduled Tasks utility (which is similar to the utility of the same name in Windows 98). Microsoft sometimes calls this utility the Task Scheduler, so don't be confused.
Get to Scheduled Tasks through the Control Panel and run the wizard by double-clicking the Add Scheduled Task icon. You can specify a program to run, a descriptive name for the task, how often the task should run (daily, weekly, monthly, at each reboot, at each logon, or once), when the task should run (time and date), and the name and password (which, by the way, cannot be blank) of the user under whose account the task should run.
Instant Answer This last item is important because many tasks (such as defragmenting a disk) require administrative rights. If you configure several scheduled tasks and a single task doesn't run but others do, you may have a problem with user rights. If you configure several scheduled tasks and none of them run, then you may suspect that the Task Scheduler service itself has been stopped, paused, or never started. (You can manually restart the service by using the Services console in the Administrative Tools folder.)
After you create a scheduled task, you can view its property sheet from the Scheduled Tasks folder to modify it further. For example, the Settings tab (see Figure 14-8) provides additional options for starting and stopping tasks, such as whether to wait for idle time before starting a task and whether to run a task when the computer is using battery power. The scheduled task object is actually a file with the suffix .JOB, and the default location is C:\WINDOWS\TASKS.
Figure 14-8: Set configuration options for scheduled tasks here.
Instant Answer You should know for the exam the meaning of the various options on the Scheduled Tasks folder's Advanced menu, as follows:
* Stop Using Task Scheduler: This one's self-explanatory.
* Pause Task Scheduler: This one morphs into 'Continue Task Scheduler' if you choose it. If the time specified for a task comes and goes while the scheduler is paused, the task doesn't run until its next scheduled time (if any).
* Notify Me of Missed Tasks: Oddly, the default for this toggle setting is off (cleared). You may see an exam question that expects you to know this fact.
* AT Service Account: Here, you name the user account for all tasks created with the command-line utility, AT. (See this section's last paragraph for more on AT.)
* View Log: This command runs Notepad with a log of the utility's actions (the file SCHEDLGU.TXT in C:\WINDOWS).
Use the task scheduler tool to schedule recurring maintenance tasks, such as running the disk defragmenter or the Disk Cleanup Wizard. Scheduled Tasks is also handy for running resource-intensive programs when you don't need the computer, for example at night.
Tip Make sure your PC's system date and time are set correctly via the Date and Time control panel. If this information is inaccurate, any tasks you have scheduled won't run when you expect them to.
Tip You may need to modify the command line to accomplish an automated task. For example, when scheduling the Backup program, you would normally specify a backup job name on the command line so that the program knows what files you want to back up, and where they should go.
A command-line version of the graphical Scheduled Tasks utility is AT.EXE. All tasks that you create by using this program must run under the same user security context, which you set in the Advanced menu of the graphical utility. The graphical utility is more flexible than AT.EXE, in that each task can run in a different user security account context.
The method for tuning application performance that's likely to be on the exam is the foreground/background split adjustment for CPU time, which I explain in the section 'Foreground/background adjustment' earlier in this chapter.
You can set the priority levels of individual processes by using the Task Manager's Processes tab. That's a bit risky, but you can experiment with the technique if you like. Just right-click a process and choose Set Priority, followed by the value you want. The values are, from highest priority to lowest, realtime; high; abovenormal; normal; belownormal; and low. Note that any priority changes you make in Task Manager remain in effect only while the process is running: If you stop and restart the process, it reverts to the default base priority level that its programmer originally coded for it.