Apr 17, 2020 The external hard drive becomes unreadable and corrupted due to carelessly disconnecting or powering down the drive without following the eject drive protocol. You can repair the unreadable external drive with a quick scan on the PC with the help of the disk checking utility and its drive repair function. Nov 14, 2019 It helps to verify and repair a range of issues related to startup HD and external drive problems. If you are able to fix the hard drive or SSD in your Mac (or an external drive) using Disk Utility you will hopefully be able to recover your files. To run Fist Aid on an external hard drive: Open Disk Utility.
Looking for a way to install and run OS X on an external hard drive? This can be useful for a couple of different reasons. Firstly, it allows you to run another copy of OS X without needing any additional Mac computer.
Corrupted External Hard Drive Mac
Also, since you can run a full copy of OS X on the external drive, it can be used for troubleshooting purposes on other Macs or it can be as a kind of virtual OS X. I’ve already written about how you can install OS X in VMware Fusion, but that takes up space on your Mac. Using an external drive, you can save space on your Mac, though it might be a bit slower if you are using USB 2.0.
In this article, I’ll walk you through the requirements and steps to install OS X onto an external hard drive.
Format External Hard Disk
The first thing you’re going to need to do is format the external hard drive properly. The file format has to be Mac OS X Journaled and you have to use the GUID partition map. To do this, open Disk Utility and connect the drive to your Mac.
Under External in the left hand menu, click on your external hard drive and then click on the Erase button. Make sure you backup any data before you erase the drive. When you click Erase, a dialog will pop up where you can configure some options.
Give your drive a name, choose OS X Extended (Journaled) for Format and GUID Partition Map for Scheme. It should only take a minute or two for the drive to be erased and reformatted. Now your drive is ready for OS X.
Corrupt External Hard Drive Mac Os X 10
Install OS X
There are two ways you can install OS X on to your external hard disk: by reinstalling OS X from the OS X Utilities repair screen or by downloading OS X from the App Store and running the installer. I’ll show you both methods in case one isn’t working for you.
The easiest way is to download OS X from the App Store. Once you open the App Store, you’ll see a link on the right for the latest version of OS X (El Capitan as of this writing).
Go ahead and click the Download button to start downloading the installer. Note that if you already have that version of OS X installed, you’ll see a popup message appear asking if you still want to continue or not. Just click Continue.
Once it has been downloaded, just double-click the installer, which will be located in the Applications folder.
Keep clicking past the license agreement, etc., until you get to the screen that asks you which disk to install OS X on. By default, it is set to MacBook.
Click on the Show All Disks button and you’ll see an icon for the different disks and partitions on the Mac. I named my external hard drive OS X and that shows up in the middle.
You can also tell it’s an external hard disk because it uses the icon with the orange hard drive. Click Continue and then follow the instructions to complete the installation. Note that your computer may restart during the install and you don’t have to do anything. OS X will automatically continue installing onto the external hard drive rather than booting up to your internal version of OS X.
At the end of this article, I’ll show you how to boot up to the external hard drive, so skip down if you ended up using the App Store method. Note that by default, the Mac will start booting up directly to the external hard drive until you change it.
The second method to install OS X is to restart the Mac and press and hold the COMMAND + R keys. This will load up OS X Recovery.
The OS X Utilities screen will appear and here you want to click on Reinstall OS X. Again, you’ll go through some basic screens, but when you get to the hard disk screen, click on Show All Disks again.
Using this method, you’ll have to login using your Apple ID and password so that the entire OS X installer can be downloaded off of Apple’s servers. Whichever method you choose, it will take anywhere from 15 to 30+ minutes to install OS X onto your external hard drive.
While OS X is installing, your computer will restart a couple of times. Note that when it finally boots into OS X, that is the version running off your external drive. To switch back and forth between the internal and external drive, you have to restart your computer and hold down the OPTION key.
When you do that, you should see at least four icons. In my case, I have five because I have Windows installed using Boot Camp. Anyway, the grey MacBook and Recovery 10.11.2 icons are for my internal OS X and the orange OS X and Recovery 10.11.3 are for the version installed on my external drive.
Use the arrow keys to select which drive to boot from and then simply press Enter. If you have a newer Mac and a USB drive that supports USB 3.0, everything should run fairly fast. Overall, it’s a fairly straight-forward process and took me less than an hour to get everything working. If you have any questions, feel free to comment. Enjoy!
Summary: This is a tutorial to repair corrupted, unreadable and unmountable external hard drives on Mac computers, but in case of losing data accidentally, you can recover your files from the external hard drive with iBoysoft Data Recovery for Mac at first.
Nowadays, people have been relying more on external hard drives, either to extend the capacity of primary storage media or to create a backup copy of important data. However, it's common that an external hard drive stops working suddenly, or becomes corrupted, unmountable, unreadable, and inaccessible on Mac. In this article, we will tell you how to repair external hard drives on Mac without losing data.
- Table of contents
- 1. How to repair external hard drive without losing data on Mac?
- 2. How to recover lost data from external hard drives?
How to repair external hard drive without losing data on Mac?
In this part, you will see 4 feasible solutions to repair external hard drives that are corrupted or not detected on Mac mini, MacBook Pro/Air, etc. And the following is a general graphic about external hard drive repair and recovery.
Solution 1: Check the IDE / SATA USB Connections
Sometimes, your external hard drive is not showing up or working normally just because of the faulty connections. Therefore, before you set about repairing this external hard drive, the first thing you can do is to check the connections.
- Step 1: Reinsert the external hard drive into another USB port or to another Mac computer.
- Step 2: Try another USB cable to connect the hard drive to your Mac.
- Step 3: Check if there any software update is available in your APP store in that an outdated driver could make your external hard drive not recognizable.
Solution 2: Repair external hard drives with First Aid
First Aid in Disk Utility is able to repair many disk problems, for instance, multiple apps quit unexpectedly, the file system of a hard disk is corrupted, or an external device doesn't work properly, etc.
- Step 1: Go > Utilities > Disk Utility.
- Step 2: Select the external hard drive you want to repair in the left sidebar.
- Step 3: Click First Aid on the top and click 'Run' to repair this external hard drive.
Solution 3: Repair external hard drives with FSCK command
If Disk Utility can't repair external hard drive and your hard drive is not readable by your Mac computer still, there is an alternative way called FSCK command that can repair your external hard drive. Try it and you may have luck with this command line.
- Step 1: Go > Utilities > Terminal.
- Step 2: Type in diskutil list to list all the connected drives on your Mac currently.
- Step 3: According to the disk information, locate the external hard drive you want to repair in the list, and then find its drive identifier.
- Step 4: Restart your Mac and, before the Apple logo appears, hold down 'Command + S' keys. This will boot your Mac into Single User Mode.
- Step 5: Some white text will scroll by quickly. When it stops, type in /sbin/fsck –fy, then press Enter.
- Step 6: Type in /sbin/fsck_hfs -fy /dev/[drive identifier] (You need to replace hfs with the file system of your external hard drive and replace [drive identifier] with the identifier of the external hard drive).
- Step 7: When fsck is finished checking and repairing the errors in your external hard drive, type reboot into the command prompt and press Enter to restart your Mac.
Solution 4: Repair external hard drives by reformatting
If FSCK command is too difficult to perform for you, another solution is to reformat this corrupted external hard drive. However, reformatting will erase all the files on this drive. Thus, you need to keep in mind that this solution can only be exerted when you don't have anything important on this external hard drive or you have backed up your important files previously.
Step 1: Go to Applications > Utilities > Disk Utility.
Step 2: Select the external hard drive and click 'Erase' on the top.
Step 3: Provide a name and a format to format the drive, and then click 'Format'.
How to recover lost data from external hard drives?
The most terrible situation is that you can neither access your important files on this external hard drive nor have any copy of data backup at hand. What's worse, when you try to fix disk errors with Disk Utility, only to be told 'Error: Disk Utility can't repair this disk. Back up as many of your files as possible, reformat the disk and restore your backed-up files.' What to do in this case? Actually, you still can get your files back with reliable external hard drive data recovery software, and iBoysoft Data Recovery for Mac is such a useful recovery tool.
iBoysoft Data Recovery for Mac is free external hard drive data recovery software, which can recover lost data from external hard drives that First Aid failed to repair and recover lost data from encrypted APFS external hard drives. What's more, when the disk is corrupted, formatted, unmountable, unreadable, or even erased, this software can still recover the lost files. This all-in-one recovery tool can restore files from emptied Trash, hard drives, SD cards, memory cards, USB flash drives, etc.
With this data recovery software, you can recover emails, photos, documents, videos, etc. on macOS 10.15 (Catalina), macOS 10.14 (Mojave), macOS 10.13 (High Sierra), macOS 10.12 (Sierra) and Mac OS X 10.11 (El Capitan), 10.10 (Yosemite), 10.9 (Mavericks), 10.8 (Mountain Lion), 10.7 (Lion).
Tutorial to recover lost data from the external hard drive
Step 1: Download and install iBoysoft Data Recovery for Mac.
Step 2: Launch this program. Select the external hard drive that needs to be repaired and click 'Next'. The program will start scanning this drive for recoverable files.
Step 3: After the scanning process finishes, you can click the found files and preview.
Step 4: Choose what you want to get back and click 'Recover'.
Having finished the hard drive data recovery with Mac data recovery software, you can fix this external hard drive by reformatting so that you can use it again.
If you can't repair the external hard drive by reformatting, probably the external hard drive has been damaged physically. In this case, you have to send it to an expert or replace it with a brand-new one.