Want to highlight a helpful answer? Upvote!

Did someone help you, or did an answer or User Tip resolve your issue? Upvote by selecting the upvote arrow. Your feedback helps others! Learn more about when to upvote >

Looks like no one’s replied in a while. To start the conversation again, simply ask a new question.

User profile for user: Charles Campbell2
Charles Campbell2 Author
User level: Level 2
162 points

External drive won't mount for new iMac

My LaCie 2Big Dock Thunderbolt 3 (12 GB RAID 0) functioned normally for many months attached to a 2015 iMac. It appeared on the desktop after any restart. I bought a new iMac and used Migration Assistant to move everything over to the new computer. It went well—only had to re-input a few passwords. However, afterwards the dock will not mount following a restart. When I unplug and replug the Thunderbolt 3 cable, or when I do a complete shutdown and then do a cold start, the drive mounts and seems to function normally until a restart. If I unmount the disk manually and then restart, the LaCie mounts normally. While it is mounted, LaCie Raid Manager says the firmware is up to date. I deleted and reinstalled the Raid Manager but no improvement. I reformatted the LaCie with both Disk Utility and the LaCie software but no change. Disk Utility says no problems in either the Mac or the LaCie. I reinstalled MacOS Catalina—all no joy… The Lacie mounts after a restart when I attach it to my MacBook Pro. I’ve tried different cables and ports…


I guess I could put up with dragging the disk to the trash before restarting, but it’s aggravating that it didn’t work as before or with my laptop… Any suggestions? Thanks.

iMac Line (2012 and Later)

Posted on Sep 19, 2020 6:03 PM

Reply
Question marked as Best reply
User profile for user: TheLittles
TheLittles
User level: Level 10
192,667 points

Posted on Sep 19, 2020 6:36 PM

Charles Campbell2 Said:

"External drive won't mount for new iMac: [...]I guess I could put up with dragging the disk to the trash before restarting, but it’s aggravating that it didn’t work as before or with my laptop… Any suggestions? Thanks."

-------


Use First Aid in Disk Utility:

Check the health of the Hard Drive - perhaps it is going dead. If so, well, then it's time for a new Hard Drive. In disk Utility, Its sectors would be looked at and maybe reset to make it operate as it should.


A. Run First Aid in Disk Utility:

  1. Open: Applications menu
  2. Select: Utilities menu
  3. Select: [This Hard Drive]
  4. Click: the First Aid button

See if this is then accessible.


B. Try Mounting Recovery Mode:

  1. Plug in: the hard drive:
  2. Hold Down: command + R upon boot
  3. Select: Disk Utility
  4. Select: [This Hard Drive]
  5. Click: Mount
  6. Click: the First Aid button

See if this is then accessible.

View in context

Similar questions

3 replies
Question marked as Best reply
User profile for user: TheLittles
TheLittles
User level: Level 10
192,667 points

Sep 19, 2020 6:36 PM in response to Charles Campbell2

Charles Campbell2 Said:

"External drive won't mount for new iMac: [...]I guess I could put up with dragging the disk to the trash before restarting, but it’s aggravating that it didn’t work as before or with my laptop… Any suggestions? Thanks."

-------


Use First Aid in Disk Utility:

Check the health of the Hard Drive - perhaps it is going dead. If so, well, then it's time for a new Hard Drive. In disk Utility, Its sectors would be looked at and maybe reset to make it operate as it should.


A. Run First Aid in Disk Utility:

  1. Open: Applications menu
  2. Select: Utilities menu
  3. Select: [This Hard Drive]
  4. Click: the First Aid button

See if this is then accessible.


B. Try Mounting Recovery Mode:

  1. Plug in: the hard drive:
  2. Hold Down: command + R upon boot
  3. Select: Disk Utility
  4. Select: [This Hard Drive]
  5. Click: Mount
  6. Click: the First Aid button

See if this is then accessible.

Reply
User profile for user: TheLittles
TheLittles
User level: Level 10
192,667 points

Sep 21, 2020 6:34 PM in response to Charles Campbell2

Charles Campbell2 Said:

"External drive won't mount for new iMac: [...]It's maddening not to be able to figure out a fix... My boot HD as well as my Time Machine external drive are encrypted, but the LaCie is not. Could that make any difference?"

-------


Some Thoughts on this:

  • Decrypting Might Make a Difference:

You'd decrypt it temporarily it using Disk Utility. Just note that security will be lost, so decrypt it at your own risk.


  • Plug it into a Different Mac:

What happens when you plug this into another Mac? Is it seen? If not, it's the drive itself.


  • Any Security Software Installed?:

Security Software would most certainly get in the way here, blocking out items that are plugged in (such as storage devices). So, uninstall the Security Software, using an Uninstaller. Get the Uninstaller from none other than the Developer themselves. Elsewise, it may end up being malware (malicious software) or spyware you sendup installing. Ask the Developer about uninstalling it, if you are unfamiliar with doing so. Restart you Mac, once uninstalled.

Reply
User profile for user: Charles Campbell2
Charles Campbell2 Author
User level: Level 2
162 points

Sep 21, 2020 5:06 PM in response to TheLittles

If I mount the LaCie manually (unplug and replug), Disk Utility says all drives are fine and the S.M.A.R.T. status is OK. I created a test user but the problem persisted. It happens in Safe Mode too. I reinstalled Catalina a second time--this time from an Internet startup (Command-option-R). Even reset NVRAM... It's maddening not to be able to figure out a fix...


My boot HD as well as my Time Machine external drive are encrypted, but the LaCie is not. Could that make any difference?


Thanks for the help.



Reply

External drive won't mount for new iMac

Welcome to Apple Support Community
A forum where Apple customers help each other with their products. Get started with your Apple ID.
Learn more Sign up