TOPIC
This article discusses when to reformat the hard drive of a Macintosh computer, with a focus upon repairing damage to the disk's formatting structure using Apple's disk utilities. An introduction to the terminology is provided.
DISCUSSION
TROUBLESHOOTING PATHS
The "Terminology" section and onward briefly introduces the concepts but is not prerequisite to using these paths. Symptoms Formatting structure damage may result in read/write errors, missing files, and files that cannot be opened, moved, copied, or deleted. Damage to the data stored upon the drive may also result, such that almost any software problem or Mac OS error message could indirectly signify formatting structure damage. Though the -127 error is a more familiar indicator than some others, the problem must be confirmed through the use of the proper disk utility whenever damage is suspected. When to Use the Paths - Path to a High-level Format : Use at any time when troubleshooting for the symptoms described, but before performing time-consuming tasks like clean-installing the operating system. - Path to a Low-level Format : Use whenever symptoms suggest that the other path may have failed to resolve the problem, or when using the disk testing function of Apple's formatting utilities: Drive Setup, Apple HD SC Setup, or Internal HD Format. The Path to a High-level Format (Fixing logical formatting structure damage) 1. Start up the computer from a disk other than the one to be repaired. If you are pressing Command-Option-Shift-Delete during startup, release the keys as soon as the startup screen appears or the hard disk may not mount. Note: This key sequence does not work with all Macintosh models and is not supported. Pressing the "c" key during startup is another method. 2. Open Disk First Aid from a disk other than the one to be repaired. 3. Does the volume to be repaired appear in the Disk First Aid window?
NO : Quit Disk First Aid. Go to step 7. 4. In the Disk First Aid window, select the volume to be repaired, then start the Repair function. Wait for it to complete. Does Disk First Aid report that the volume appears to be OK or that it was repaired successfully?
NO : Repeat this step once. If the answer is the same, continue to the next step. 5. Does Disk First Aid report that problems were found but it cannot repair them?
NO : Continue to the next step. 6. Disk First Aid reports that it cannot start or continue the repair because of some other problem.
7. Shut down the computer and disconnect all external devices except the keyboard, mouse, and monitor. If the disk to be repaired is among them, leave only it connected. Start up the computer from a system disk and open Drive Setup, Apple HD SC Setup, or Internal HD Format (the "Utilities" section of this article explains which to use). Does the disk to be repaired appear in the disk utility's window?
NO : Stop. There may be a hardware problem. NOTE: Internal HD Format may not locate the disk if it is using a hard disk driver installed by another utility, including Drive Setup. If there is any doubt, use Drive Setup instead. 8. If you are arriving at this step for the second time, go to step 11 now. Open Drive Setup or Apple HD SC Setup (the "Utilities" section of this article explains which to use). Internal HD Format cannot be used in this step because it has no separate option to install the hard disk driver. If possible, use Drive Setup; otherwise, go to step 11 now. Is the button or the menu command to "update" the driver dimmed?
NO : Continue to the next step. 9. Update the hard disk driver. Did the driver install successfully?
NO : Go to step 12. 10. The version of the hard disk driver already installed may be newer than what the disk utility installs. The most current version of each Apple utility can be downloaded from Apple Software Downloads . If you are using Internal HD Format, download Drive Setup instead. If there is no newer disk utility, go to step 12 now. If a third-party hard disk driver is installed, it should be updated with the utility that installed it. The Knowledge Base contains information about how to identify hard disk drivers . Use the newer disk utility to try updating the driver again. Could the driver be installed?
NO : Go to step 12. 11. Try using a newer version of Disk First Aid, if available. The most current version of Disk First Aid can be downloaded from Apple Software Downloads . If there is no newer version, either continue to the next step now, or try using a different disk repair utility. A list of commercial disk utilities is available at the bottom of this article. Will you try a different disk utility or a newer version of Disk First Aid?
NO : Continue to the next step. 12. Initialize the disk using the appropriate Apple formatting utility. If using Drive Setup, do not configure it for a low-level format (a high-level format is the standard setting). CAUTION: Formatting a disk permanently erases all information from it. If possible, copy important files to another disk first. If a third-party hard disk driver is installed, Apple's formatting utilities may not be able to format the disk, though newer versions may work. Use a third-party disk utility if necessary. The Knowledge Base contains information about how to identify hard disk drivers . 13. Did the format complete successfully?
NO : Continue to the next step. 14. Was the unsuccessful format performed by Apple HD SC Setup or Internal HD Format?
NO : Continue to the next step. 15. Was the unsuccessful format performed by Drive Setup or by another utility configured to perform a high-level format? (A high-level format usually takes less than a minute to complete; a low-level format takes much longer.
NO : Stop. There may be a hardware problem. The Path to a Low-level Format (Fixing physical formatting structure damage) 1. Follow the steps provided in "The Path to a High-level Format" until instructed to stop. Note that neither path will fix a hardware problem. 2. Start up the computer from a disk other than the one to be repaired. 3. Was the disk just formatted by Apple HD SC Setup, Internal HD Format, or another utility configured to perform a low-level format? (A high-level format usually takes less than a minute to complete; a low-level format takes much longer.)
NO : Continue to the next step. 4. Is this a PCI-based computer? (PCI-based computers include the PowerBook 3400 and all PowerBook G3's and later, plus all Power Macintosh computers other than the 6100, 7100, and 8100 series.)
NO : Go to step 8. 5. Open the System Folder of the current startup disk (not the disk to be repaired), then open the Extensions folder inside. Is the Insomnia extension present?
NO : Continue to the next step. Figure 1: Insomnia 6. Open the Apple menu and select Control Panels. Is Energy Saver among the Control Panels, and can it be opened successfully?
NO : Continue to the next step. 7. PCI-based Macintosh computers may go to sleep during a disk test if left unattended for longer than 30 minutes, causing the test to fail. Choose one of the following preventive measures before continuing to the next step.
2. Create a startup disk that includes both the Energy Saver control panel and the Energy Saver extension, placed into their respective places in the System Folder. After starting up from that disk, open the Energy Saver control panel and set each control to "Never." 3. Create a startup disk that contains the Insomnia extension in the Extensions folder. This extension can be obtained from the System Folder of system CD's that include it. 8. Open the appropriate Apple formatting utility from a disk other than the one to be repaired, then start the "Test Disk," "Test," or "Scan For Defects" function, depending upon the utility. The test may take as long as an hour or more to complete, depending upon the disk. Did the disk utility report that no errors were found, or that they were corrected or recovered?
NO : Continue to the next step. 9. Before low-level formatting, it is best to isolate the computer from external devices first, as they may prevent it from completing successfully. Shut down the computer and disconnect all external devices except the keyboard, mouse, and monitor. If the disk to be formatted is among them, leave only it connected. 10. Low-level format the disk. Apple HD SC Setup and Internal HD Format always perform low-level formats, but Drive Setup will not unless first configured to do so: select "Initialization options" from the Functions menu, then click "Low-level format." CAUTION: Formatting a disk permanently erases all information from it. If possible, copy important files to another disk first. If a third-party hard disk driver is installed, Apple's formatting utilities may not be able to format the disk, though newer versions may work. Use a third-party utility if necessary. The Knowledge Base contains information about how to identify hard disk drivers . Did the format complete successfully?
NO : Stop. There may be a hardware problem. TERMINOLOGY LOW-LEVEL FORMAT
Because it recreates the physical formatting structure, low-level formatting may repair damage to it that cannot be repaired by sector sparing with Drive Setup or other utilities, but erases the disk in the process. Low-level formatting requires much more time to complete than a high-level format. Smaller disks require at least several minutes; larger disks as much as an hour or two or more. HIGH-LEVEL FORMAT
These structures support the HFS (hierarchical file system) volume that is created in the process, represented by the disk's icon on the desktop. A high-level format thus completes the process of preparing the disk to receive the operating system and any user data. A disk driver is also written, handling write and read functions to and from the hard disk. Because it recreates the logical formatting structure, high-level formatting repairs damage that cannot be repaired by Disk First Aid or other such utilities, but erases the disk in the process. It does not verify or repair physical formatting structure problems. High-level formatting typically requires less than a minute to complete, and often only a few seconds. INITIALIZATION
SECTOR SPARING
Sector sparing can also be performed by the Test Disk function of Drive Setup and other Apple formatting utilities, which scans a disk for bad sectors by checking the integrity of blocks of data read from and copied back to the disk. This function takes about as long to complete as a low-level format, but has the key benefit of not erasing the disk in the process. Because the Test Disk function does not perform low-level formatting, some bad sectors that might have been repaired by doing so will only be spared. However, this difference is rarely significant enough to warrant low-level formatting except where Test Disk fails a disk or recommends it be low-level formatted. UTILITIES
Apple HD SC Setup is for use with SCSI hard drives in 68K Macintosh computers (non-Power Macintosh computers). Apple HD SC Setup always performs a low-level format followed by a high-level format. Apple HD SC Setup can verify and repair the physical formatting structure of a hard disk without reformatting. Internal HD Format , now obsolete, was Apple's formatting utility for IDE hard drives before support for those drives was brought to Drive Setup. Use of Drive Setup is preferred. Internal HD Format always performs a low-level format followed by a high-level format. Unlike the other two utilities, it does not provide a separate option for installing the hard disk driver alone. Internal HD Format can verify and repair the physical formatting structure without reformatting. Disk First Aid is Apple's utility for verifying and repairing the logical formatting structure of Macintosh volumes. It cannot create, verify, or repair the physical formatting structure of a disk, nor can it high-level or low-level format any disk. OVERVIEW: WHEN TO HIGH-LEVEL FORMAT A HARD DISK OVERVIEW: WHEN TO LOW-LEVEL FORMAT A HARD DISK - When the physical formatting structure of the disk has become damaged and cannot be repaired by sector sparing with a compatible disk utility. - When, even after several attempts, a high-level initialization fails to complete successfully. FREQUENTLY ASKED QUESTIONS What causes formatting structure damage?
- Software-related crashes or conflicts due to corrupt or incompatible applications, extensions, and system software. - Incompatible hard disk drivers. - Malicious applications like viruses. - Not restarting or shutting down the computer properly. - Hardware-related crashes or interference due to a variety of possible issues with internal or external devices and their cabling, termination, or firmware. - Problems with RAM and other expansion hardware. - Electromagnetic interference (EMI) and power fluctuations (brownouts and overvoltages). - A damaged physical formatting structure. Physical formatting structure damage can be caused by some of the same things that cause logical formatting structure damage and by areas of real damage to the surface of the disk itself, like scratches or pits; also by degradation or contamination of the disk surface or drive heads due to smoke, dust, or particles of the disk media itself. Why would a format fail?
A high-level format will fail when the formatting utility is unable to successfully write the logical formatting structure to the hard disk, often due to bad sectors. In that event, low-level format or use a disk utility to spare bad sectors before attempting another high-level format. After repairing the formatting structure, is the data on the disk still good?
What if Disk First Aid and another disk utility disagree?
When do I "Zero all data"?
Zeroing-out is not to be confused with "disk zeroing," a phrase sometimes used to refer to the process of creating the master directory block, volume bitmap, and catalog file. If a low-level format repairs damage that a high-level format cannot, and may also repair some damage that sector sparing cannot, and if a high-level format is quickly and automatically performed after the low-level format anyway, why ever perform anything but a low-level format? Because low-level formatting:
- Can take a long time to complete. - Removes information, such as the computer's serial number, that may be recorded in an otherwise protected area of the disk. Not all Macintosh computers have this sort of information recorded onto their stock hard drives, but many do. The serial number of an iMac, for example, can be conveniently viewed in Apple System Profiler 2.x, but only if the hard drive that contains it has never been low-level formatted. The part number of the software bundle it shipped with is also provided. THIRD-PARTY SOFTWARE ALTERNATIVES CAUTION: Before using any third-party disk utility, ensure first that it is compatible with the computer, the version of the Macintosh operating system, and the HFS format in use. Alternatives To Disk First Aid Disk First Aid is entirely capable of diagnosing logical formatting structure problems on Macintosh-formatted volumes. Alternative utilities may be used in circumstances where a "second opinion" is desired, and may provide other useful functions beyond those necessary to diagnose the formatting structure, such as disk optimization, erased file recovery, and hardware diagnostics. What follows may not be a comprehensive list. MacMedic , by Total Recall Software Norton Utilities , by Symantec Corp. TechTool Pro , by Micromat Computer Systems Alternatives To Apple's Formatting Utilities
DiskWorks , by Micronet Technology, Inc. FormatterFive , by Software Architects, Inc. Hard Disk Toolkit , by FWB Software Silverlining , by La Cie, Ltd. |
Document Information | |
Product Area: | Peripherals |
Category: | Magnetic Storage Devices |
Sub Category: | SCSI Disk Drives |
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