What You Will Need
Utilities: To fix your hard drive you will need Disk Utility, which comes free with any Mac computer. Alternatively, you can use a program like Drive Genius, available from Prosoft Engineering. You don’t need both utilities. We tend to use Drive Genius because faster than Disk Utility. A hard drive: To what extent you are able to revive a broken hard drive depends on how bad a state the drive is in. Try not to rely on the drive as your primary storage system, as even if you are able to revive the device there’s no guarantee of its longevity. Use it to hold temporary or backup data. A current backup: The process outlined in this guide will erase the drive data, so any data that’s currently on the drive needs to be backed up if you want to save it. If the drive is preventing you from backing up the data, you’ll need to recover the data before you try to revive the drive. A number of third-party data recovery utilities are available, such as Data Rescue, Techtool Pro, and Disk Warrior.
Install the Drive in an External Enclosure
Installing the hard drive in an external enclosure allows you to run the drive utilities from the Mac’s startup drive. This makes for a faster process and avoids the use of a DVD or other startup device, which you would need if you were trying to revive the Mac’s internal startup disk. You can still use this process, but the instructions for booting from another startup drive are not included in this guide.
What Type of Enclosure to Use
Any enclosure that accepts your drive’s interface will work fine. Most likely, the drive you’re attempting to revive uses an SATA interface. The specific type (SATA I, SATA II, etc.) doesn’t matter as long as the enclosure can accommodate the interface. You can connect the enclosure to your Mac using USB, FireWire, eSATA, or Thunderbolt. USB will provide the slowest connection; Thunderbolt, the fastest. You’ll want an external drive dock that lets you plug in a drive without any tools, and without having to open an enclosure. This type of drive dock is intended for temporary usage, and it ensures that the drive does not damage any internal interface components.
Attempt to Mount the Drive
The first step in reviving the hard drive is to determine whether or not it is even a candidate for revival. To do this, you will need to confirm that the drive can respond to and perform basic commands. First, make sure the drive is powered on and connected to your Mac, then turn on your Mac. The Mac will either a) recognize the drive and appear on the desktop, b) display a warning that the drive is not recognized, or c) not respond to the drive’s connection whatsoever. If your Mac does not respond to the drive connection at all, try shutting down the computer, powering off the external drive, and then restarting in the following order: If the drive still does not appear, or if you don’t receive the warning message, you can try the following:
Shut down the Mac and change the external drive to a different connection. Use a different USB port or change to a different interface, such as from USB to FireWire.Swap out the external for a known good drive, to confirm that the external case is working correctly.
Failing these workarounds, the drive is likely beyond saving.
Erase the Drive
The next step assumes that the drive either appeared on your Mac desktop or you received a warning message stating the drive is not being recognized. If you receive errors at this point, the chances of the drive successfully completing the revival process are diminished. Drives that fail to erase as instructed are more likely to fail in the next step as well.
Scan for Bad Blocks
This next step will check every location of the drive to determine which sections are writable. The utilities used in the following instructions will mark any section that is unable to be written to or read from as a bad block. This prevents the drive from using these areas later. All drives, even brand new ones, have bad blocks. Manufacturers expect drives to not only have a few bad blocks but to develop them over time. They plan for this by reserving a few extra blocks of data that the drive can use, essentially swapping a known bad block for a reserved one. In the first set of instructions we will use Drive Genius, and int eh second we will use Apple Disk Utility.
How to Scan for Bad Blocks With Drive Genius
The scan process will begin. After a few minutes, it will provide an estimate of the time needed. In most cases, this will be anywhere from 90 minutes to 4 or 5 hours, depending on the drive size and the speed of the interface. When complete, Drive Genius will report how many, if any, bad blocks were found and replaced with spares. If no bad blocks were found, the drive is ready to use. If bad blocks were found, proceed to the section titled Drive Stress Test.
How to Scan for Bad Blocks With Disk Utility
When Disk Utility uses the Zero Out Data option, it will trigger the drive’s built-in Spare Bad Blocks function as part of the erasure process. Depending on the size of the drive, this process may take as little as 4-5 hours to as much as 12-24 hours. Once the erasure is complete, if Disk Utility shows no errors, the drive is ready to use. If errors occurred, you likely will not be able to use the drive.
Drive Stress Test
Now that you have a working drive, you may wish to put it in service right away. If you plan to commit important data to the drive, you may wish to run a stress test. This is a drive stress test, sometimes referred to as a burn-in. The purpose is to exercise the drive by writing and reading data from as many locations as possible for as much time as you can spare. Any weak spot will reveal itself now rather than down the road. There are a few ways to perform a stress test, but in all cases, we want the entire volume to be written to and read back. Once again, we will use two different methods.
How to Perform a Stress Test With Drive Genius
After a few minutes, Drive Genius will provide an estimate of the time needed. In most cases, this will be anywhere from a day to a week, depending on the drive size and the speed of the drive interface. You can run this test in the background while you use your Mac for other tasks. When the test is complete, if no errors are listed, you can feel confident that your drive is in good shape and can be used for most activities.
How to Perform a Stress Test With Disk Utility
When Disk Utility uses the DOE-compliant 3-pass secure erase, it will write two passes of random data and then a single pass of a known data pattern. This will take anywhere from a day to a week or more, depending on the size of the drive. You can run this stress test in the background while you use your Mac for other activities. Once the erasure is complete, if Disk Utility shows no errors, you’re ready to use the drive knowing it is in great shape.
