Seagate portable HDD (USB 3) not recognised.

Question

Seagate portable HDD (USB 3) not recognised.

Hi guys.

I have a 1 Tb & 2 TB Seagate portable hard drives running off USB 3. Until today I could read the drives on all my Apple devices. However, although the drives spin up, they no longer show up in either finder or disk utility on my Mac Pro (2013) nor my MacBook Air (2011). Both work just fine on my Mac Mini.

A Samsung 1 TB portable drive which my partner is using as a backup for her MacBook Pro does not work on my Mac Pro or the MacBook Air either. I have other drives attached to my MacBook Pro via USB which are working fine, and plugging other peripherals into my MacBook Air via USB does not cause any problems.

I can't believe it is a power issue, particularly with the Mac pro, and the drives are formatted correctly. Any ideas for solving this problem would be appreciated. Thanks in advance.

Stephen

Mac Pro (Late 2013), OS X El Capitan (10.11.2)

Posted on Jan 9, 2016 8:46 AM

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Answer 1

lllaass

Level 10

210,519 points

Jan 9, 2016 8:50 AM in response to stephenalewis

What shows under USB in System Profiler?

OS X: About System Information and System Profiler - Apple Support

You should see both the enclosure as well as the HD inside

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Answer 2

Jan 9, 2016 9:26 AM in response to lllaass

Hi IIIaass

Thanks for getting back to me. The drive does not show up in system profile. Here's a screen shot;

Thanks

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Answer 3

lllaass

Level 10

210,519 points

Jan 9, 2016 9:43 AM in response to stephenalewis

You said "A Samsung 1 TB portable drive which my partner is using as a backup for her MacBook Pro does not work on my Mac Pro or the MacBook Air either."

Does that drive still work on here MacBook Pro?

Profiler partially identified the enclosure which tends to indicate a bad enclosure.

Have you tried another cable?

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Answer 4

Jan 9, 2016 12:30 PM in response to lllaass

The Samsung still works fine on her MacBook Pro, and I've tried 3 different cables. The reference to "Backup+" in the list is my Seagate 8Tb backup drive, not the 2Tb portable going me problems.

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Answer 5

lllaass

Level 10

210,519 points

Jan 9, 2016 12:45 PM in response to stephenalewis

- Try resetting the SMC and NVRAM/PRAM

Intel-based Macs: Resetting the System Management Controller (SMC)

About NVRAM and PRAM

- Try starting in Safe Mode

OS X: What is Safe Boot, Safe Mode?

- Boot to Recovery and repair the startup disk

OS X: About OS X Recovery - Apple Support

Also when in Recovery see if Disk Utility sees the external drive

- If it is repairable reinstall the OSX

How to reinstall OS X on your Mac - Apple Support

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Answer 6

Jan 10, 2016 1:54 PM in response to lllaass

Ok guys.

Problem solved. I took the cable off the Mac Mini and tried it on the Mac Pro; The drives worked fine!! So went out and bought a new (quality) cable and all's well. Thanks for the input.

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