Check Hard Drive Health of a Mac with Disk Utility
It’s a good idea to check the hard drive health of a Mac as part of a periodic maintenance routine. Doing this is extremely easy with Disk Utility, and we’ll cover exactly how to verify hard disks, how to repair them, and what to do if you encounter any issues or errors in the process. This works for all hard drives, whether it’s an internal drive, an external drive, or a boot disk, though the process is slightly different for boot drives. Let’s begin.
Checking Hard Drive Health
The first thing you’ll want to do is check the hard drive health, this is done with a process called verification, and it’s quite simple:
- Launch Disk Utility, found within the /Applications/Utilities folder
- Select the Mac hard drive from the left side menu and click on the “First Aid” tab
- Click on “Verify Disk” in the lower right corner and let it run
You will find the window populating with messages about the drives health, messages that indicate things are fine appear in black, messages that indicate something is wrong appears in red. Disk Utility should resemble something like the following screen shot:
For the vast majority of users, what you see will look something like this, finalizing with a message of “The partition map appears to be OK”, indicating that no errors have been found:
Verifying partition map for “APPLE Media”
Checking the partition list
Checking for an EFI system partition
Checking the EFI system partition’s size
Checking the EFI system partition’s file system
Checking all HFS data partition loader spaces
Checking Core Storage Physical Volume partitions
The partition map appears to be OK
If you do see a red message saying something along the lines of “Error: This disk needs to be repaired” you can just choose to click the “Repair Disk” button to start that repair process, that will work for any internal or external drive – unless the drive in question is your boot disk, then you will find the “Repair Disk” button is inaccessible. That doesn’t mean you can’t repair the boot drive though, it just requires an additional step which we’ll cover next.
Repairing a Boot Disk with Disk Utility
In this case all you need to do is reboot into the Recovery HD partition and run Repair Disk from there, here’s how to do that in OS X Lion, Mountain Lion, and OS X Mavericks.
Before proceeding it’s a good idea to backup your drive quickly with Time Machine.
- Reboot the Mac and hold down Command+R (hold own Option key on some Macs)
- Select “Recovery HD” from the boot menu
- Choose “Disk Utility” from the Mac OS X Utilities screen
- Click the hard drive that reported the error, click the “First Aid” tab, and now click on “Repair Disk”
After Repair Disk has ran successfully, you are free to boot OS X as normal and the drives issues should be resolved.
A few final notes: relying on a hard drive being healthy is not an alternative to having backups, you need to backup your Mac with regularity using Time Machine or some other method if you choose. Hard drives fail, it’s a fact of computing life. It’s also important to note Disk Utility isn’t a 100% conclusive test suite to determine drive health, and if you hear weird sounds coming out of the hard drive it’s probably a good time to head down to Apple and prepare for a drive swap because that drive is likely going to croak soon.
Finally, if you need to perform further maintenance on the disk, then you may need to use fsck to repair the drive, which is a bit more complex and requires the usage of the command line.