I have accidentally disconnected 3TB external hard drive without ejecting it first. Now when I run disk utility to repair disk, it says: "Disk utility can't repair this disk. Back up as many of your files as possible, reformat the disk, and restore you backed-up files." Is there anything else I can do to repair this external hard drive or recover the data?
It is a common problem that can cause data loss after external hard drive becomes corrupted. Sometimes, disk utility is able to repair corrupted external hard drive, but sometimes, disk utility cannot repair external hard drive which is caused by some reasons, such as file system corruption.
Two error types about disk utility cannot repair the disk
There are two error types about disk utility cannot repair the disk as below:
1. Disk utilily cannot repair this disk. You can still open or copy files on the disk, but you cannot save changes to files on the disk. Backup the disk and reformatt it as soon as you can:
2. Disk utilily cannot repair this disk. Back up as many of your files as possible, reformat the disk, and restore you backed-up files:
External hard drive becomes corrupted, we cannot access the data stored on it, if we click "Erase" button, although we can access external hard drive after reformatting, but we will lose all data stored on it, if we don't reformat external hard drive, we cannot access it, so the first thing is to recover data from external hard drive after disk utility cannot repair external hard drive.
Recover data from external hard drive in Mac
M3 Mac Data Recovery is the professional Mac data recovery software which can recover data from external hard drive that disk untility cannot repair, recover data from formatted, unmountable, uninitialized, corrupted drive, recover deleted or lost files in macOS 10.12 and Mac OSX 10.11/10.10/10.9/10.8/10.7/10.6 and supports HFS, HFS+, exFAT and FAT32 file systems.
Tutorial to recover data from external hard drive with M3 Data Recovery
Step 1: Download, install and then launch M3 Mac Data Recovery on your Mac computer.
Step 2: Select "In a specific volume" option or select "In a specific hard drive" option and then choose the external hard drive that disk utility cannot repair from the drop-down list.
Step 3: M3 Mac Data Recovery is scanning lost data from the external hard drive
Step 4: Select the found files you expect to recover and then click Recover to recover lost data from external hard drive.
Reformat external hard drive that disk utility cannot repair
After data recovery is successfully done from external hard drive, please reformat and then it will be working again.
Step 1: Launch Disk Utility from Utilities.
Step 2: Click the icon for your external hard drive in the sidebar on the left.
Step 3: Click the Erase tab along the top of the window and enter the related information.
Step 4: Click the Erase button to start reformat operation.
About disk utility
Disk Utility is the name of a utility, created by Apple, for performing disk-related tasks on Mac OS. These tasks include:
Creation, conversion, backup, compression and encryption of logical volume images from a wide range of formats read by Disk Utility to .dmg or, for CD/DVD images:.cdr
Mount, unmount and eject disk volumes (including hard drive, removable device and disk images)
Enable or disable journaling
Verify a disk's integrity, and repair it if the disk is damaged
Erase, format, partition and clone disks
Secure deletion of free space or disk using a 35-pass Gutmann algorithm
Add or change partition table between Apple Partition Table and GUID Partition Table
Create, destroy and repair RAID sets
Restore volumes from Apple Software Restore (ASR) images