Hi, My 5Tb passport hard drive won't mount on Mac. The hard drive is visible in the disk utility (work fine on Windows and been format in ExFat format). To mount it with the WD soft: nothing happened. Disk Utility can fix certain disk problems—for example, multiple apps quit unexpectedly, a file is corrupted, an external device doesn't work properly, or your computer won't start up. Disk Utility can't detect or repair all problems that a disk may have.
When your Macintosh HD (disk0s2) is not mounted in Disk Utility, your Mac computer won't turn on. How to fix it and rescue the data?
This post has 5 methods to fix Macintosh HD (disk0s2) not mounted issue.
Method 1: Repair disk with Disk Utility
- Ever since the update I have been unable to mount my Seagate Backup Plus Drive. I've tried restarting multiple times, connecting to other computers (which does work, they all mount it just fine) and checking Disk Utility. The drive shows up greyed-out in Disk Utility, pressing mount doesn't do anything.
- Couldn't boot and couldn't repair it in Disk Utility.' Haris had kept his 2012 MacBook Pro's original hard drive, so he swapped it in place, and it wouldn't boot.
After your Mac computer won't boot, you can boot your Mac into macOS Recovery mode and then repair unmounted Macintosh HD (disk0s2).
Steps to repair unmounted Macintosh with Disk Utility:
1. Turn on your Mac by pressing Power button.
2. Press and hold down Command+R keys immediately upon hearing the startup chime. Hold down the keys until you see the Apple logo, a spinning globe or other startup screen. Startup is complete when you see the macOS Utilities window as below:
3. Select Disk Utility and click Continue.
4. Select the unmounted Macintosh HD (disk0s2) from the left sidebar of Disk Utility window.
5. Click 'First Aid' in the toolbar of Disk Utility window.
6. Click Run to check and repair file system errors.
Wait until the procedure is complete. If you get returned a message saying success, restart your Mac and see if your Mac can be booted.
If another message says that disk utility cannot repair the disk, go to next solution.
Method 2: Repair Macintosh HD (disk0s2) with Terminal
If Disk Utility failed to repair the problematic Macintosh HD (disk0s2), you can try to fix it with Terminal.
1. Boot your Mac into macOS Recovery mode.
2. Click Utilities from the menu bar and select Terminal from the drop-down list.
Disk Not Mounting Mac
3. Enter diskutil list command to list available volumes.
4. Enter diskutil repairVolume/disk 1s.
Replace disk 1s with the volume identifier of your Macintosh HD (disk0s2).
Method 3: Recover data from unmounted Macintosh HD (disk0s2)
To rescue data from unmounted Macintosh HD (disk0s2), you need a professional data recovery software.
As a professional Mac data recovery software, M3 Data Recovery for Mac can recover data from unmounted, corrupted, unreadable Macintosh HD (disk0s2).
Besides that, M3 Data Recovery for Mac recover deleted files even emptied from Trash, recover data from formatted drive, recover data from deleted/lost APFS partition, etc. on macOS.
Steps to recover lost data from unmounted Macintosh HD (disk0s2)
1. Run M3 Data Recovery from macOS recovery mode.
2. After M3 Data Recovery for Mac is loaded, select Macintosh HD (disk0s2) from the storage device list and click Next.
3. M3 Data Recovery for Mac is scanning the lost data from the unmounted Macintosh HD (disk0s2).
4. Preview documents, photos and play videos, audios, etc. in preview mode.
5. Select found files and then click Recover to start data recovery.
Method 4: Restore from Time Machine backup
If you have a Time Machine backup, you can restore the backup and fix unmounted Macintosh HD (disk0s2).
Format flash memory mac. 1. Boot your Mac into macOS Recovery mode.
2. Select Disk Utility and click Continue.
3. Select Macintosh HD (disk0s2) and click Erase.
Before erasing, make sure you don't lose any data.
4. Return to macOS Utilities window.
5. Select 'Restore from Time Machine Backup' and click Continue.
6. Select your Time Machine backup disk as the restore source and then click Continue.
7. Select a backup and then click Continue.
8. Select the hard disk as the restore destination and then click Restore to continue.
9. Restart your Mac computer when the restore is done.
Method 5: Erase the drive and reinstall macOS
If there is no important data or you have recovered lost data successfully, erase the Macintosh HD (disk0s2) and reinstall macOS.
1. Boot your Mac into macOS Recovery mode.
2. Select Disk Utility and click Continue.
3. Select Macintosh HD (disk0s2) and click Erase.
4. Return to macOS Utilities window.
5. Select 'Reinstall macOS' and click Continue.
Mac Disc Won T Mount
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tl;dr version: An external disk wouldn't mount; I panicked and tried to fix it, then I just gave up and it fixed itself – specifically, the fsck_hfs daemon fixed it for me.
Yesterday, I rebooted my the Mac mini in my office into Windows to play some games, then when I rebooted back into OS X, my Drobo wouldn't mount.
The status lights on it were all normal, and the Drobo Dashboard (which coincidentally I think failed with ‘missing components' necessitating reinstalling) reported it was healthy too, but while the drive showed in System Information and in the Disk Utility tree, if I tried to mount it it just reported that it couldn't, and suggested that I should try to repair it.
I was a little nervous of doing this since a Drobo uses an unusual disk structure, but its own support documents say you should indeed try repairing the disk if it fails to mount. (It's not actually surprising, since the Drobo's unusual system should be entirely hidden from the Mac; so far as the Mac is concerned, it should be just like any other disk.)
Disk Utility, however, reported that the disk was unrepairable. Now, I tried connecting it using USB 2.0 (rather than FireWire 800), and connecting it to another Mac, but still, no dice. I was beginning to resign myself to buying Disk Warrior to laboriously reconstruct the directory structures, but I wasn't quite done troubleshooting yet.
My next step was to connect it to yet another Mac, and now I got a faint glimmer of hope. This was my wife's MacBook Air, which is still running OS X 10.9; both my Macs had been upgraded to 10.10. Clicking on iStat Menus, I saw that the fsck_hfs process was running, taking up a lot of the CPU. This is a background process that checks and repairs disks, so with nothing to lose — and knowing that a Drobo support document I read earlier said that if fsck is running, let it complete — I just left it and went to watch telly.
I came back a couple of hours later, and boom; the Drobo was mounted on the desktop of my wife's Mac. Now, one detail I omitted earlier was I had noticed that when the Drobo was connected to either of my Yosemite Macs, a process called diskarbitrationd grabbed a whole chunk of the CPU. Good paint program for mac. Googling it suggested it's a process just concerned with mounting disks, so I had thought it was getting stuck because it couldn't mount the Drobo. I can't find information to suggest diskarbitrationd is a successor to or incorporates the repair elements of fsck, but it's possible that had I just left the Drobo connected to the Mac mini when I first noticed the problem that it would have repaired itself there too. I'm a little annoyed that the Mac apparently had the ability to repair the disk, but loading Disk Utility and clicking Repair – the obvious troubleshooting process – failed with no hint that an invisible, background process was actually capable of doing it, not least because if you know less than I do, you'd just assume that your data was gone, and either start a lengthy restore process or start spending money on new disks.
(The data on the Drobo – mostly our iTunes Library – was backed up, online, to Livedrive, but the idea of downloading 4TB data, even on a fibre connection, wasn't one to fill me with delight.)
Hard Drive Not Mounting Mac
I'm pretty paranoid about backup and data security, but this episode was a reminder that however you protect your data it's never absolutely safe; all you're doing is reducing the risk. The Drobo system allows for a single disk (or, depending on your configuration, two disks) to fail mechanically without losing any data – just pop out the duff disk and slot in a new one, something I've done in the past – but as I was reminded even this doesn't ensure the data is secure, since it only protects against one particular (albeit major) source of data loss.
It's important to point out that I believe the Drobo system itself was entirely blameless in all of this; I think the fault was one that could have affected a simple single-disk USB drive, and would have been fixed in the same way.
