Mac OS X Tools Overview

Mac OS X comes with a number of utilities that can provide insight into the operation of the computer. Three major tools that are only for Mac OS X are Disk Utility, Console, and Terminal.

Disk Utility

Disk Utility for Mac OS X combines some of the features of Disk First Aid and Drive Setup, which are separate utilities that require Mac OS 9. Using Disk Utility, you can:

• Obtain information about a hard disk, including its format, capacity, and number of files

• Verify and repair any Mac OS Standard (HFS), Mac OS Extended (HFS Plus), or UFS formatted disk

• Erase the contents of a hard disk, CD-RW disc, or DVD-RW disc

• Partition a hard disk

• Set up a Redundant Array of Independent Disks (RAID)

• Create disc image files, such as from hard disks or optical discs

• Burn (write) disc image files to optical discs

Disk Utility is installed with Mac OS X in the Utilities folder, within the Application folder. To launch Disk Utility, double-click its icon. By default, Disk Utility displays the startup disk at the top of the list on the left, with additional mounted hard disks, optical discs, and disk images below.

The Macintosh computer in the illustration has one hard drive named iMac, and there's a CD in the optical drive, plus an unmounted disk image.

If a disk fails to appear in the left-hand column, it means Disk Utility could not locate it. If the disk's cables are connected properly and it is getting power, it may have become damaged to the extent that the Mac OS no longer recognizes it. If that's the case, you'll need to resort to more powerful disk recovery tools (discussed later in this lesson).

If a disk does appear, it is listed by its capacity and manufacturer. Below the disk in the left-hand column should be the names of one or more partitions on that disk. To perform an action on either a volume or a partition, select the drive; the available options appear in the window to the right.

Information

For information on storage devices attached to the Mac, select the drive and click the Info icon in the toolbar.

First Aid

Just because Disk Utility can properly locate and list a disk does not mean that all is well with that disk. It's a good idea to periodically perform basic disk repairs, so click the First Aid tab. As its name implies, First Aid can repair only minor disk damage.

Before making any repairs, you may want to make a full backup of the disk to ensure you can always revert to the disk's state in the unlikely event that the repairs actually exacerbate a bad situation.

If you select a startup partition, you can't verify or repair its catalog and directory structure, because doing so on a live startup disk might make your Mac inoperable. (You must start up your Mac using the Mac OS X Install disc, and use the Disk Utility available on that disc to verify or repair the disk.) You can verify or repair only the disk permissions that control which users can access various files and folders. For example, if a customer complains that a Mac fails to retain the preference settings, it may be because the customer no longer has permission to change the necessary files. In such a case, it's a good idea to click Repair Disk Permissions. (If you want only to check for errors but not fix them, click Verify Disk Permissions instead.) When Disk Utility is done, repeat the repair process until Disk Utility indicates that no repairs were necessary.

If you select a partition that is not the startup volume, you can verify or repair its catalog and directory structure but not its permissions. Again, if Disk Utility indicates that it discovered problems after you click Repair Disk, repeat the process until you get a clean bill of health. Mac OS 9 users have this repair functionality in the Disk First Aid utility.

Remember, the options available in the First Aid tab are just that—your first line of defense against minor disk injuries. For more serious trauma cases, you'll want to rely on more powerful third-party tools such as Micromat's TechTool or Alsoft's DiskWarrior.

Erase, Partition, and RAID

The remaining three tabs in Disk Utility do not have any troubleshooting features, so they are discussed only briefly to familiarize you with their overall functions.

The Erase tab is useful if you've tried everything you can to repair a disk and it's simply not recoverable. In this case, you can start over from scratch by reformatting the disk. All data is lost when you erase, so use this as a last resort only. Erasing a disk is also a good idea before replacing it, to ensure that sensitive data is not inadvertently passed on to the next owner of the drive. Mac OS 9 users can erase disks in the Drive Setup utility.

The Partition tab enables you to divide a large hard disk into smaller logical volumes, each of which appears on the Finder desktop with its own name. Novice users often are confused when presented with multiple volumes, so use partitions only when necessary to satisfy a particular need. Partitioning a hard disk, or removing partitions from a hard disk (so that you can treat it as a single volume again) both cause all data to be lost, so don't partition a drive with out giving it serious forethought. Mac OS 9 users can partition disks in the Drive Setup utility.

The RAID tab enables you to logically combine multiple drives into a single volume, creating what is known as a RAID. Whereas partitioning makes one drive seem like many, creating a RAID makes many drives appear as one. The primary benefit is either data redundancy, or much faster performance because the burden of reading/writing is spread over multiple drives. Mac OS 9 users cannot create RAIDs in the Drive Setup utility.

Console

Console is installed with Mac OS X in the Utilities folder, within the Application folder. Double-click its icon to launch Console, which immediately opens a window displaying the Macintosh computer's log files.

These log files record error messages from applications and background processes. These files can help you troubleshoot problems because they might contain:

• More detailed information than what you see in error messages

• Informative messages that are not displayed anywhere else

• Progress messages

• Messages that might be useful to a developer or technician assisting you with an issue

Console Exercise

1.	Launch Console.
2.	Click the Logs icon in the upper left, then double-click system.log. Note the date and time of the last entry (if one exists).
3.	Choose System Preferences from the Apple menu.
4.	If necessary, move the System Preferences window so that you can see the Console window.
5.	In the System Preferences window, click Network. Choose Built-in Ethernet from the Show pop-up menu, choose Using BootP from the Configure IPv4 pop-up menu, then click Apply Now.
6.	Look at the Console window. You should see some new messages.

The first part of the message gives you the date and timestamp. The next part names the owner of the process. The next part lists the process IDs and then the reason for the error. When no error occurs in the GUI and you cannot determine why a network application has stopped working, Console's error messages might help direct your probing.

Terminal

Terminal is installed with Mac OS X in the Utilities folder, within the Application folder. Double-click its icon to launch Terminal, which immediately opens a window displaying a command-line interface.

If you're a longtime Mac user accustomed to graphical user interfaces that you can figure out by exploring visible options, this virtually empty window with a command-line interface will probably leave you stumped. The fact is, unless you're familiar with UNIX, the Terminal application won't do you much good. However, if you are experienced with UNIX, there are many commands you can enter here that will aid in troubleshooting.