If you need this tutorial, you’ve messed up.
Trying to recover data from a hard drive is a last resort. You should never need to do it.
Instead, you should have a solid backup plan in place. If you do, you’ll never need to worry about your data getting corrupted or a hard drive failing. You’ll always have a safe copy somewhere.
If the worst does come to the worst and you accidentally delete a file, a hard drive gets corrupted or totally fails then this tutorial will explain what to do and lay out your options.
A Good Backup Plan
As I mentioned above, a good backup plan will save you a lot of pain and heartache if a hard drive fails. Once you recover the data you lost, you’re going to want to backup everything up straight away so lets consider what a good backup looks like. A safe backup has:
- A local backup of everything. This is something like Time Machine which creates hourly backups of all your files. If you accidentally delete something or otherwise lose data, this is your first place to look.
- An offsite backup of everything. While keeping all your data on a second hard drive in your house offers a lot of protection against data loss, it doesn’t do much against a fire or theft. If something can take out all copies of your data in one go, it’s not a good backup. For that reason you need an offsite backup. This can be an online service like Backblaze or just a hard drive you regularly update and leave in a friend’s house.
- An online, accessible backup of your important files. Getting data back from online services can take time if you’ve got a slow internet connection. It also may not be immediately accessible. You should keep a copy of all your important digital files somewhere you can get to them. I use Dropbox but you could use iCloud Drive or even your own server. If you’re concerned about privacy, you can encrypt them.
The Different Kinds of Drive Failures
There are three different ways to lose data on a hard drive.
- You delete a file in error
- The file system gets corrupted so it can’t be read, although most of the data is still there. This can happen because of a malware infection, or just an OS bug
- The worst, the drive physically fails. This can be anything from the click of death to a shattered hard drive platter
Different drives are more likely to fail than others. For example, SSDs are safer from physical damage and external drives are more susceptible to it. Backblaze conducted an analysis of the hard drives they used and found an average annual failure rate of 5.84%. With hard drives, it’s not a matter of if they’ll fail, but when and how they fail.
How easy the data is to recover depends on what’s gone wrong. If you accidentally deleted something recently, then the chances of recovering it are quite good. If the drive has physically failed, the odds of getting anything back are slim.
1. Protect the Disk
As soon as you think you’ve lost data on a hard drive, stop using it. Continuing to try to write or read information from the drive can only make things worse. If you’ve accidentally deleted a file, the bits where it is stored are more likely to be overwritten; if the drive is corrupted or if the hard drive is physically damaged, using it can cause it to break further. Before starting to recover data, you need to make sure no more harm comes to your data.
If it’s an internal hard drive, shut down the Mac. If it’s an external one, disconnect it.
2. Make the Drive Accessible
If the data you’ve lost is just accidentally deleted or on an external hard drive you can skip this step. If you’ve lost data from a Mac’s internal drive, the best way to recover it is using a second Mac. A Mac that has a corrupted or broken hard drive will not run stably. Using a second Mac also gives you a safe location to restore the data too.
With Target Disk Mode you can boot a Mac so that other Macs view it as an external hard drive. With this you can safely recover your data to the second Mac.
Jay Inman has written a full tutorial about Target Disk Mode which you should read before continuing. In brief, you need to connect the two Macs using a FireWire or Thunderbolt connection and then hold down T while the one you want to recover data from boots.
3. Select a Data Recovery Tool
Finder isn’t capable of recovering lost or damaged data from a hard drive so you need to use a specialised data recovery app. While there are lots of them out there, they all do pretty much the same thing.
Install the chosen app on the Mac you are using for the recovery. Using any of them is relatively straightforward. They scan the hard drive you are recovering data from and reconstruct all the data they find regardless of whether it’s been deleted from the index or not.
You can browse the file system in a Finder-like window and select the files you want to recover to the second Mac. If a file is easy to recover, these apps will do it.
4. Consider Forensic Recovery
For deleted files and corrupted data, you can often successfully recover it yourself as long as you act swiftly. If the data is badly corrupted or the hard drive physically damaged, however, consumer tools won’t cut it.
For data that you absolutely need to get back, you should consider forensic data recovery. Specialist companies can deconstruct and repair certain kinds of failures. This is, unfortunately, an incredibly expensive option.
You can expect to pay 10 or 15 times what you paid for the drive in the first place. Most companies will do a free or cheap evaluation so you can at least find out what the chances are before spending a fortune.
Having to recover data from a hard drive is not fun. It’s expensive, unreliable and time consuming. It’s often not even possible—at least, not without spending hundreds of dollars. The best way to avoid it is to have a solid backup plan in place. If you don’t, you’re leaving yourself open to a lot of pain.
If the worst does come to the worst, boot the Mac in Target Disk Mode, use another Mac and an app to try and recover as much data as possible and, failing that, consider paying the experts.