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Resolved rMB occasionally doesn't recognize external drives

ApolloBoy

ApolloBoy

macrumors 6502a
Original poster
Apr 16, 2015
778
305
San Jose, CA
I'm having a bizarre issue with my rMB, every now and then it doesn't recognize external drives, whether it's a flash drive, hard drive or an optical drive. It does this with both my USB-C hub (https://www.amazon.com/VicTsing-Female-Charger-Adapter-Chromebook/dp/B01BSJVY7Y) and my USB-C adapters (https://www.amazon.com/Adapter-Rank...&qid=1470191811&sr=8-5&keywords=usb-c+adapter), and the only way to totally fix it is to do a restart (and of course it wears off after a while). Is anyone else having the same issue?

EDIT: Updating to Sierra totally resolved this problem, I've been on Sierra for a week as of this edit and my external drives get recognized every single time as they should be. Glad that Apple squashed this bug flat.
 
Last edited:
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You're on OS X 10.11.3 or 10.11.4, correct? This is a bug introduced in 10.11.3 and fixed in 10.11.6. Update your OS X install and it will go away.

It drove me crazy.
 
Is it after sleep? My experience with the bug (a different bug, I guess) was that after eject the USB drive would not re-mount without a reboot. For me that experience has ended.
 
Admiral said:
Is it after sleep? My experience with the bug (a different bug, I guess) was that after eject the USB drive would not re-mount without a reboot. For me that experience has ended.
Click to expand...

Same thing here. And the 'experience' is still here, only rebooting helps.
 
This is odd, when I tried plugging in one of my external drives through a USB 3 cable my rMB wouldn't recognize it, but when I tried the same drive with a USB 2 cable it worked fine (albeit at a slower speed of course). Hmmm...
 
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ApolloBoy said:
I'm having a bizarre issue with my rMB, every now and then it doesn't recognize external drives, whether it's a flash drive, hard drive or an optical drive. It does this with both my USB-C hub (https://www.amazon.com/VicTsing-Female-Charger-Adapter-Chromebook/dp/B01BSJVY7Y) and my USB-C adapters (https://www.amazon.com/Adapter-Rank...&qid=1470191811&sr=8-5&keywords=usb-c+adapter), and the only way to totally fix it is to do a restart (and of course it wears off after a while). Is anyone else having the same issue?
Click to expand...

Yeesh. If you wanted to use external drives so much, should have gotten a MacBook Pro. ;):p
 
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ApolloBoy said:
external drives,
Click to expand...

Please, which makes and models?

Have you tried a new cable and if so, what was the brand?

If a drive is limited to USB 2.0, then that may be a factor. 2.0 is sometimes described as not ideal for storage.

(I'm seeking reliable information about 3.0 and C.)
 
I'm in the same boat here. I use the dell USB-C hub and, in order to make it work, I have to restart the Macbook every morning. Otherwise it only recognizes the screen, all other USB devices are not recognized.

Pretty annoying to say the least. Mine is the latest Macbook, top specs, and latest OS.
 
Same here.
USB 3.0 not recognized. No problems with USB 2.0 drives or other USB devices. My Elgato eye TV usb stick works fine when connected with Anker usb3.0 to USB-C adapter.

I use an USB-C data cable for my HDD (seagate), not an adapter. Still doesn't work.
 
My rMB has never had a problem recognising USB drives or any other USB devices. However, every now and then it fails to detect my WD 500 GB HDD. A restart is the only solution.
 
For me, the previously seeded build usually failed to automatically mount some or all of the non-startup volumes that are on the same disk as the startup volume. Hard disk drive, USB 2.0.

With the currently seeded build, I have not noticed that problem.
 
Build 16A294a of pre-release macOS Sierra

A recurrence of the problem.

HFS Plus startup volume (encrypted with Core Storage), three other HFS Plus volumes (without Core Storage) on the same disk.

The operating system failed to automatically mount one of those three.

No coincidental hogging of the CPU.

If the MacBookPro8,2 is compatible with HDAT2 on UBCD, I might perform a thorough check of the disk. I expect that check to take a few days.
 
ApolloBoy said:
This is odd, when I tried plugging in one of my external drives through a USB 3 cable my rMB wouldn't recognize it, but when I tried the same drive with a USB 2 cable it worked fine (albeit at a slower speed of course). Hmmm...
Click to expand...

Thanks. I tried this and it works for me as well.
It is not how it should be but it is a relatively nice workaround in some cases where I just need to check my external HDD or want some smal files without having to reboot my rMB.
 
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@ApolloBoy if you like, edit the subject line/title of your opening post to show that the topic is resolved.

(Not the Edit button. There's an unlabelled cog icon.)
 
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