Force an External Mac Drive to Mount via Command Line Terminal Commands in Mac OS X

If you can't get an external hard drive or USB flash drive to mount when you plug it in your Mac, you usually open Disk Utilities and try from there. If that doesn't work, try this Command Line technique in the Terminal Application on Mac OS X.

Our video describing how to do it in the GUI in Disk Utility is here:

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Thanks for watching!

[dominykasvanagas]

I am using youtube for more than 10 years and I have never written a single comment. Man, I thought I have lost 2TB of videos of the last 13 years. Thank you very much.

[jackbrownvideography]

This is the only Youtube video or website that has helped me with this problem. This dude deserves a Nobel Peace Prize for this!! If this is your first time using this video, BOOKMARK IT ASAP.

[marquiscityyt]

I seriously don’t know how to thank you.My 5TB external Drive with over 1TB of files on it wouldn’t show up. I spent over two hours watching YouTube videos and none of them worked, except this one. You’re a life savior.

[thomasmcnamara]

Incredible! Thank you so much for putting this together. Here I was thinking I lost over 14 TB of data, and about to surrender and ask for a refund or replacement from WD, and I found your video. I followed the steps and although mine did not launch/mount automatically, I followed the advice of someone in the comments who said to wait 60-90 mins as it can take a while to rescan drive. Came back later and the drive had mounted and I have my files back! Amazing amazing amazing!

[elasticlimit]

Thanks SOOO much. In the end I just had to force quit FSCK_HFS in Activity Monitor. Worked like a charm. Your commenters saved my life! Many thanks all!

[LukeMaximoBell]

If it says resource busy you need to change "hfs" in the last command. Try to change it out to "Microsoft Basic Data".

if that doesn't work, when you type "diskutil list", then replace "hfs" in the final command with whatever is in front of the name of your hard drive.

[kosatka]

God bless u was about to get a mini heart attack when all the other methods didn’t work.

[skewedhorizon]

I'd watched half a dozen other videos that ranged from changing a connection cable to simply using Disk Utility but this video solved my issue. The list command prompted the hard drive to appear in Disk Utility so I didn't have to go futher that that, but it was great to see my drive pop up there. Thank you

[bugsyoptics]

didnt work for me last mount line says "/Volumes/usb failed with 1"

[tablemannerz]

This video has helped me more times than I care to admit! I recently upgraded to an M1 iMac Running Monterey. I have an external HD (Western Digital 6tb). After connecting it to my iMac upon transferring a very very small file my whole computer hung. I later read through Mac forums that Western Digital announced that it is a known issue with M1 Monterey for external drives particularly the 4tb to hang. Anyways, This process totally worked and I was able to retrieve my drive. I'd also like to note for anyone reading this - I previously tried to use diskutil and first aid as well as using terminal to unmount and mount. All things failed - but the sudo drive technique seems to always work! THANK YOU!

[lucarugiero]

I love you. I have never felt this feeling for another man before.

[moimiumiu]

YOU SAVED MY LIFE!!!! THIS WORKS!! The light of my hard drive was on but since last night that I disconnected it without unmounting it, my laptop wasn't recognizing it. I followed these steps and it immediately appeared back!

[thusspokeenki]

For anyone who got “/Volumes/usb failed with 1”, just leave your drive plugged in for 30-90 minutes to see if it pops up. Catalina takes forever to rescan some hard drives after they’ve been improperly ejected, like mine. Hope this helps.

[ZIZZOWORLDMUSIC]

what about the actual internal Mac Hdd if not showing into disk utility? Can be used the same method without losing the data?

[anamaunahan]

This worked for me!


I had to use these commands in Terminal after doing the sequence in your tutorial:
diskutil unmountDisk /dev/disk2
diskutil eject /dev/disk2


I removed my hard drive then plugged it in after and then it worked.


Thank you so much!

[ClaudiuAgapieMusic]

Hi- for a Raid 0 system (i have 3 ssds in raid 0 config, in one OWC thunderbay via thunderbolt connection) - what commands i must use to force mounting them? cause suddenly i am unable to mount the raid anymore - i have 6 tb with all my work there... i am ruined if i cant access it anymore - Please help!

[openalias]

Thank you so much for this video! Unfortunately, external drives seem to have gotten much more fickle, especially if accidentally disconnected. This process has helped me to mount 20+ TB (yes TB) of hard drives-one of which I thought I was gonna have to have repaired. I've liked, saved, shared, and more. Thank you!!!

[davidhuante]

I literally never leave comments even though I always use Youtube, but I spent the last week trying to figure out what was going on with my hard drive. Ended up wiping my whole computer and getting back to the latest OS but then couldn't access my drive to get my old files. So many sites, articles, comments - and your video helped me fix it and made my computer mount my device. Thank you SO

[jordancyphers]

Thank you for this video. I have a big promotions test that I'm studying for, and all of my study info is on my external hard drive that wouldn't mount. This video was a lifesaver! Thank you!

[annerusso]

I literally can not thank you enough! I have tried everything and thought I lost 20 YEARS and 3TB of my kids lives plus family, friends and professional photos I have taken!!! You are amazing! If you can recommend any online photo storage for someone who has done personal and some professional photography over the years, please advise me! I am so sick of being at the mercy of these drives going down.
Again, THANK YOU SOOOO VERY MUCH!!!