Stellar Knowledge Base

macOS is unable to recognize the external drive, and Disk Utility can’t mount it. How to recover data from the unmounted drive on Mac?

 Modified on: August 19, 2021 |    56649 views

The external hard drive going unrecognized might be giving you nightmares since you are unable to access your important documents, videos, photos, audio files? Don't worry since this KB article shares a unique solution to recover data from an unmounted or unrecognized drive on macOS Catalina, Mojave, High Sierra, Sierra, El Capitan, Yosemite, Mavericks, Mountain Lion and Lion. 

 An unmounted drive appears Greyed out in Disk Utility (image only for reference)

First and foremost connect your unmounted drive to Mac. Further, download, install the Stellar Data Recovery Professional software and perform below sequential steps:

Step 1) Launch Stellar Data Recovery Professional on Mac

Step 2) From the interface, select the type of data you want to recover. Click Next.

Mac data recovery unmounted drive

Step 3) Under Select Location window choose your unmounted drive. Click Scan to launch the scan process on an unmounted drive.

Select unmounted Mac external drive

After a while, the scanning process completes successfully.

Step 4) Next, from the list of found files and folders listed in – Classic List/ File List / Deleted List, select the desired one to launch its Preview.


Step 5) Lastly, select all desired files and folders and click Recover to save. 

unmounted data recovery mac

Image for Reference

This completes the data recovery process from an unmounted or unrecognized drive on macOS. Below is the video tutorial for your understanding:-


50 User Comments

Hi, i di use stellar phoenix version 4 on my powerpc mac. It run about 1 1/2 days and came up with results. I saved the scan. The applications documentation promises that one can resume restore from a saved scan. I shut down my mac and later wantedt to c ontinue with restoring using the saved scan file. THIS DOES nOT WORK. AM i doing something wrong or does the software simply does not have this feature?


found the solution myself:
the disk in question is external. so it may mount at different mount point after unmount/restart etc.
In my saved scan file the disk was expected at /dev/rdisk2, but when I resumed the restore it was mounted at /dev/rdisk3 - thus the saved scan file was useless for stellarphoenix4.
Simply editing the file did work - resuming a restore is possible.

If the current version of stellarphoenix behaves the same, dear developers. please fix this. You cannot expect to find a disk at the same mount point when using a saved scan.



Thanks Kp.gores,

We will definitely work on the suggestions.

Thanks & Regards,
Amit Pandey

Amit Pandey

Almost seems to easy.........will be trying it soon and will report the volume recovery steps listed in the KnowledgeBase.


Considering Stellar Recovery for Mac OS X Lion and WD external drive unmountable, after I changed permissions and locked it in the "Get Info window" trying to restrict access, after having received lots of spam mail. Since disk did not boot, I replaced it with new internal disk and have it external. Disk utility does not permit to verify or repair it.

Thanks a lot!


I downloaded your evaluation version for Mac. In the system requirements you specify at least a G4, Leopard and Power PC compatibility. I have a G5, Leopard and, of course a PowerPC, but the downloaded file only runs on Intel.

So, do you have a version that runs on PowerPC?


Jose Sosa

Hi Jose Sosa,

If you see under free download button their is a link of Power PC User's Download here. Or you can directly download from here:


Amit Pandey

I downloaded the trial on my older intel iMac and scanned an external drive that had been partially re-partitioned by mistake, and then lost power during that process. The drive is inaccessible. It has taken 3 days to complete the propgress bar and has sat for another day with the progress bar at 100%. The program seems to be running. This is a 1.5tb drive. Ideas?

Michael Topel

Hi Michael,

Please find the possible solution for your query:

1) Kindly check if the Mac recovery software is generating on the fly preview while scanning your hard drive. If the preview is flashing on the screen then leave the Mac until the entire scan is finished (It will take time because of the HDD size). Once it completes you would be able to recover those previewed files.

2) If the scan is running without any sort of preview then cancel the scan. As you mentioned you lost power while re-partitioning the drive, there are high chances of the partition getting instantly corrupted due to halt. Run disk utility to fix errors existing on the partition. You should also try Stellar Volume Repair ( to analyze the directory structure of the hard drive partition.

Amit Pandey

i did a quick recovery on my external hard drive and it finished then i saved the files but they wont open in anything


Hi Kyle,

We would like ask few questions like - did you save the files to a volume other than the one you scanned with the software. Recovered files should be saved to a different location.

Also, at the time of scan did you check the preview of recovered files before saving them to Mac? If the files preview were fine then they should open normally after you save them. But if corrupted files are recovered it will fail to generate preview and will not launch even after saving it to desktop.


Amit Pandey

Hi folks,

My ext hard drive stopped mounting due to a power spike I guess, ran the scan and it came back with all my directory structure and files.. very exciting. I paid my money and recovered the files, and it all looks perfect but the files are all unreadable (primarily different types of video files, but also jpgs.

Why are the recovered files unusable? Is there a setting somewhere or a trick that I'm missing?

Many thanks,



Hi Richard,

Are all videos & image files unreadable or some of them are not showing?
Stellar Mac data recovery will recover your data from the external hard drive even if its in corrupted form.

I suggest you try to run a MOV repair or JPEG repair software to see if the corrupted files can be repaired.


Amit Pandey

Hi Amit,

Thanks for getting back. Yes, all the files in their correct directory structure appear on my recovery list, however all of the files are unplayable once recovered. Would you have a recommendation for a good video file repair utility?

Many thanks,



Hi Richard,

we have Stellar MOV Repair tool that fixes corrupt mov files.
If you have any other video formats then please search appropriate tool for the same, I don't have any idea about other video repairing tools.


Amit Pandey

hello. i get to the point where I have selected from the list on the left, it shows up on the right window, I go to press the "recover" button, and it's not responding. heartbreak. am i doing something wrong. please help. again, the recover button is not responding to my clicking.


Hey Greg,

We'd recommend you to uninstall & reinstall the software and then try again. It should work after reinstallation.

Let us know for further query!!

Amit Pandey

Hi I'm trying to recover some files from an unmounted external drive, but when I select it on the 'Select Volume' stage and press 'Scan' I instantly get told "No Data Found". The only way I can seem to recover the files is if I use the 'Raw Recovery' or 'Photo Recovery' options. Which is okay but sorts all the recovered files into mass grouped folders putting all the jpgs, avi, mp3 etc together despite on there original location on the uncounted drive.

Personally I don't feel like trawling through 1.6 TB of files and trying to work out where they belong! :/

Any idea how I can sort this?


Hi Charles,

Please find answer to your query below.

'No data found' message will come in case of unmountable volumes only, if File System Area of Volume is Zero filled or heavily damaged. In this case we can't recover data in originally hierarchy.
Raw recovery and Photo Recovery option will only help in this case as you told.
There is no original data hierarchy in both options. You have to choose selected file format for both option to recover only needed data.

Quick, Formatted and Deleted recovery for HFS+ only works if File System Area not completely damaged. Once try with Formatted/lost file recovery.

Hope this helps!! Do report back.

Amit Pandey

I have a failed external 3 TB ExFAT HDD. Disk Utility cannot recognize it. I would like to know if your software can read the disk before buying. I downloaded ToolBox and MacDataRecovery demo versions and both fail to find the disk.
1. Is this a limitation of the demo versions or the disk is so damaged that your products cannot mount it at all?
2. Is there any way I can test if I can use one of your products to repair or recover my disk?

Jose G.

Hey Josh,

Detection of a failed hard drive depends upon the level of corruption. Mac data recovery can read a logically corrupted drive but not a physical one. May be your drive is physically damaged or severely corrupted. We recommend you try Stellar Volume Optimizer to check if it is scanned by the tool for repair. You can download from here

Note: This tool repair logically corrupted HFS, FAT HDD but doesn't repair any physical damage. Good Luck.

Amit Pandey

I followed all these steps and quite a bit of my data was recovered but there is still some missing and a lot of files with .part extensions. Is there anything I can do about those? Thank you!



You can manually add .part file type to the header section of the software. To add file extension follow below steps:

1) Run Stellar Mac Data Recovery.
2) Click Preferences button on the main user interface or select Preferences option from
StellarPhoenixMacDataRecovery menu.
3) Click Add Header button in Preferences window. Add Header window open.
4) Browse to the location of file type you want to add.
5) Drag n drop the file at the place where 'Drag 10 sample files here' is written. You need to add 10 samples / files of the same type (.part) to include it in the list of supported file types.
6) Name of the added file type will be listed in the right hand side box
7) Type in header file name in the dialog box and then select the header file type from Select Group drop down list and the Add Header Automatically screen 37 size from Put Average Size of File text box.
8) Click Add Header button.

Now run scan again and this time the software will scan & recover drive for .part file(s).

Hope this helps!!

Let us know your further query.

Amit Pandey


I lost a HFS+ partition on a drive that had two partitions (one FAT and one HFS+).

I ran the program, and it identified 36 (yes, 36) partitions, of different sizes and formats (FAT, HFS, NTFS).

Which one am I supposed to try to restore?..


The application will show each and every volume which was created on the disk, User needs to identify the volume as per the size of the lost volume

For any further queries ask the customer to contact technical support at

Amit Pandey

Hi I have stellar phoenix and when i am trying to find my external hardisk in deleted file option it does not show the exfat partition but just shows hfs+ do i recover data from expat partition on mac.plz help

Rohit Chaudhary

Hi Rohit,

Hope you are well!!

Could you please mail us the screenshot of the drive list menu. You can send us on amit.pandey[@]stellarinfo[dot]com

Amit Pandey

My Stellar Mac recovery on a 931.5GB (1TB) NTFS laptop 2.5 inch drive shows 19 lost volumes and 9 Advanced volumes. with about 1/4 of the drive left to scan.
Q: Which one am I supposed to pick to recover? Advanced volumes found are all large, ranging from 387.27GB to 930.99 GB. Cumulatively there obviously cannot be more than 1TB of recoverable data.
Q: How are the volumes cross referencing the same data? I see 17 green lost volumes found on the processed blocks display, which does not add up to 19+9=28, where are the other 11 lost volumes?

Ron Werbos

Hi Ron,

You need to locate the volumes as per size of the volumes lost. Software is showing list of all the volumes(created, existing and deleted).First try the lost volumes. If it fails then try the Advance volume.

Hope this helps!!

Let us know for further query, if any.

Amit Pandey

Hi, after lost data i try your software to recover data.volume is fat 32 and 4,56Go.How many time restore file is taking , because now it is running since 3 hours and no progress bar show only "Analyse en cours"
in this way i don't know if soft is running or down ??




Hi Fred,

Could you please let us know the recovery option which you are using to scan FAT Volume?

Do let us know so that we can revert back in order to solve your query.


Amit Pandey

How long does it usually take to scan an external 1TB drive?
...and when it is scanned how long will it take to retrieve my files?? THANKS


Hi Blade,

There is no exact time duration of hard drive scan because scan time depends upon below factors:

1) The size of your hard drive. More number of sectors to be scanned in case of bigger hard drives
2) Condition of the hard drive which is to be scanned. At times, the software takes longer time due to presence of bad blocks on the hard drive.
3) Logical corruption also increases the scan time drastically.
4) Time to save the recovered files from the external hard drive to another media depends upon the size of files to be saved.

If your 1 TB external hard drive is healthy then the software should take only few hours (3 - 5 hours) to scan it completely. Once the scan is over, you can preview your files and retrieve them.

Hope this helps!!!

Amit Pandey

Thank you Mr Pandey for your quick response.
It seems that the scanning process is taking a lot of time even though it was quite fast at the beginning. I an running the RAW recovery scan simply because the QUICK scan did not recover all my files. It recovered ALL of the FOLDERS but some of them have 0 bytes therefore the folders are empty. i only assume that Raw recovery will be more targeted and successful. ANY WORDS OF ADVICE or ANY POINTERS on methodology?


Hi Blade,

Please find below information for each data recovery features, other than Quick Scan:

1) Advance Scan: If your hard drive data was lost due to formatting or erasure of the media.
2) Deleted Recovery: If your files were lost due to permanent deletion from the Mac hard drive.
3) RAW Recovery: When your hard drive is corrupt or logically damaged and other options are unable to scan the drive.

Let us know how exactly you lost your data from the Mac hard drive. Try scanning with different data recovery option.
Hope this helps!!

Amit Pandey

Hi again
Performing RAW recovery due to the fact that my external disk would not mount on the desktop. After failing to recover ALL data (recovered some but not all) with quick scan, I am know trying with RAW recovery. It seems that the process has stopped (or it is very very slow...scanning 1 file at a period of every few hours). What do I do in this case?. Can I stop the process and hit the recover button?? or I let it continue which may take several days if not week judging from the progress bar??


Hi Blade,

Seems like the external hard drive have issues and therefore not mounting on Mac desktop. If RAW Recovery is taking forever time to complete the scan I advise you use ‘Create Image’ option to create disk image (DMG) file of the external hard drive. Once the DMG is created the software will scan the Dmg file to recover files from it.

Hope this helps.

Amit Pandey

Hi, just a few questions.

I'm recovering a WD EHDD 1TB since my macbook pro (osx yosemite) can no longer recognize and mount it. I ran a scan and fortunately the software was able to detect all my files. I'm now transferring 300gb worth of file to my Seagate EHDD 1TB. I've been transferring for a little over 2 hours as of writing and it's still transferring the same file from when I started (based on the filename) and I checked the Seagate drive in finder only to see it's only got a few kBs transferred in. Is this normal for large volume transfers? And how long would this probably take to complete?



Hi Patch,

The software itself doesn’t have any limitations on saving large files to a media. The slowness might be due to the slow read/write speed of the destination disk. I recommend you choose another drive or save the data to Macintosh HDD and later copy it to your external media.

Hope this helps. Do let us know your further query, if any.

Amit Pandey


I am trying to recover an unmountable 3 TB external raid drive. I have tried both the quick and advanced scan. It seems like it gets stuck at the very end. The entire blue bar is filled but it still says scanning in progress. It's been around 30 hours. Is there any hope? Do you know what else I should try?

Thank you!


Jennifer Mattera

Amit Pandey

Hi Jennifer,

Stellar Mac Data Recovery software doesn't support recovery from RAID hard drives.


Hello! I'm considering your solution but can it read from a WD My Passport Essential? I heard there is hardware encryption on them :/


Amit Pandey

Hi Erdal,

If Disk Utility is showing your WD My Passport Essential device then Stellar Mac Data Recovery will list it for data recovery. Further, the software supports data recovery on encrypted hard drives however you need to unlock the HDD using its password. It doesn’t recover from the encrypted drives whose password is lost or forgotten. Hope this helps.


my mac book doesn`t WD my book duo 2x4TB anymore.
mac data recovery did find lost volume with 7,27 TB and is scanning it since 2 days in quick scan/recovery mode.
"updating directory entries (xxxxx) please wait". Any chance that it will have success? Any idea who long it will/could take?


my mac book doesn`t WD my book duo 2x4TB anymore.
mac data recovery did find lost volume with 7,27 TB and is scanning it since 2 days in quick scan/recovery mode.
"updating directory entries (xxxxx) please wait". Any chance that it will have success? Any idea who long it will/could take?


My WD My book duo 2x4TB duo is not visible on MacBoook anymore. Maca data recovery found lost volume with 7,27 TB, I run quick scan/recovery since 2 days "updating directory entries (xxxxxxx) please wait". Any chance that it will be successful?
How long it normally takes to scan?


My WD My book duo 2x4TB duo is not visible on MacBoook anymore. Maca data recovery found lost volume with 7,27 TB, I run quick scan/recovery since 2 days "updating directory entries (xxxxxxx) please wait". Any chance that it will be successful?
How long it normally takes to scan?


My WD My book duo 2x4TB duo is not visible on MacBoook anymore. Maca data recovery found lost volume with 7,27 TB, I run quick scan/recovery since 2 days "updating directory entries (xxxxxxx) please wait". Any chance that it will be successful?
How long it normally takes to scan?


...after 4 days of scanning Mac Data recovery dissappeard over night...?


We believe that your computer might have been restarted or turned off while scanning the hard drive.

We request you to perform the scan again and let us know the outcome of it, your reply is awaiting.



User Comments



Stellar Data Recovery Professional for Mac Stellar Data Recovery Professional for Mac software is a DIY tool to recover critical documents, emails, photos and videos from any storage media based on macOS Monterey, Big Sur, Catalina, Mojave, High Sierra, and older versions.

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