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User profile for user: Wanderglobe
Wanderglobe Author
User level: Level 1
6 points

USB Drive Constantly Disconnects/Reconnects

I have a Mac Mini that constantly disconnects and then reconnects my external drive. I have tried different cables and all USB ports. The cables are fine as the drive is read without issue on my PC as well as my PS4. If I plug the drive into my USB hub it stays connects. This only happens when plugged directly into the Mac.


The drive worked fine for years until I upgraded to High Sierra from Mavericks a few weeks ago. It's a 2TB Toshiba formatted with exFat. Any ideas?

Mac mini (Late 2012), OS X Mavericks (10.9.4)

Posted on Aug 31, 2018 7:58 AM

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User profile for user: leroydouglas
leroydouglas
Community+ 2024
User level: Level 10
183,798 points

Posted on Aug 31, 2018 8:05 AM

Try resetting NVRAM/PRAM http://support.apple.com/kb/ht1379



1. Shut down the computer.

2. Locate the following keys on the keyboard: Command, Option, P, and R. You will need to hold these keys down simultaneously in step 4.

3. Press and hold the Command-Option-P-R keys.

4. Turn on the computer.

5. Hold the keys down until the computer restarts and you hear the startup sound for the second time.

6. Release the keys.

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User profile for user: leroydouglas
leroydouglas
Community+ 2024
User level: Level 10
183,798 points

Aug 31, 2018 8:05 AM in response to Wanderglobe

Try resetting NVRAM/PRAM http://support.apple.com/kb/ht1379



1. Shut down the computer.

2. Locate the following keys on the keyboard: Command, Option, P, and R. You will need to hold these keys down simultaneously in step 4.

3. Press and hold the Command-Option-P-R keys.

4. Turn on the computer.

5. Hold the keys down until the computer restarts and you hear the startup sound for the second time.

6. Release the keys.

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User profile for user: woodmeister50
woodmeister50
User level: Level 6
19,717 points

Sep 4, 2018 9:24 AM in response to Wanderglobe

The issue is likely that it is drawing too much power if it

is a bus powered drive or periodically makes power demands

that are more that the USB port on the Mini can provide. This

is kind of proven when using a USB hub.


Apple seems to strictly control USB powering much more than hubs

and more so than most PCs.


I have seen this scenario before and using a hub is the only solution

or using a drive with its own power supply.

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User profile for user: Wanderglobe
Wanderglobe Author
User level: Level 1
6 points

Sep 4, 2018 10:11 AM in response to woodmeister50

That's an interesting observation and would explain the issue. I'm not sure why this was included in a later OS by Apple as the issue had never happened before. Maybe it was a tweak to increase battery life for newer macbooks. Be nice if there was a switch to disable it though. I find when macs constantly connect and disconnect hard drives they corrupt data.

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USB Drive Constantly Disconnects/Reconnects

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