Mac doesn't mount a USB pendrive (disk) without being restarted

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Mac doesn't mount a USB pendrive (disk) without being restarted

Hello guys.

For the last few weeks my mac (mid-2010 white unibody, running on High Sierra) is showing this symptom. Whenever I insert a USB disk it doesn't mount it. The disk mounts only after I restart the Mac.

This is happening to any USB disk that I have tried.

I have checked the system profiler where the disk is not listed before the restart. I have tried mounting via Disk Utility, Terminal (it says try readOnly option), and simply by disconnecting-and-reconnecting the disk.

I have to restart every time if I need to mount the disks. Any solutions please.

Posted on Nov 17, 2019 12:45 AM

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Answer 1

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BDAqua

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250,253 points

Nov 26, 2019 5:51 PM in response to parkash

Pretty strange!?

Have you done a PRAM reset, CMD+Option+p+r...

http://support.apple.com/kb/HT1379

In fact, do 3 in a row, takes a bit of time.

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

http://support.apple.com/kb/HT3964

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Answer 2

BDAqua

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Nov 26, 2019 9:30 AM in response to parkash

As a test disconnect the 1 TB external hard drive that uses 500 mA & see if the others mount without a restart.

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Answer 3

BDAqua

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Nov 17, 2019 7:08 AM in response to parkash

See how many milli Amps your USB stuff is using, I think you may need an AC powered USB Hub.

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Answer 4

parkash Author

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Dec 7, 2019 4:26 AM in response to BDAqua

Thanks again. It seem to have worked. For the past few days I do not need restarts for the USB sticks to work. I guess multiple PRAM resets did it.

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Answer 5

BDAqua

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Nov 17, 2019 5:14 PM in response to parkash

Yes, it'd be helpful to see if they're mounted how many mA it uses.

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Answer 6

parkash Author

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Nov 25, 2019 10:43 PM in response to BDAqua

Thanks again for your response. I finally checked the mAs required by my various disks. The 2 USB sticks I use need (current required) 100 mA and current available was 500 mA. The 1 TB external hard drive I use as the Timemachine requires 500 mA and current available is 500 mA for it as well.

Hence, I don't think it's the issue of the current deficiency.

Any other suggestions?

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Answer 7

parkash Author

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Nov 26, 2019 5:43 PM in response to BDAqua

Thanks for the reply. I tried that but unfortunately they do require a restart for mounting. Another thing that I have noticed is that after a restart, a disk can be mounted and unmounted for a number a times (probably 3-4 times) within a few hours and then the mac just doesn't mount it. For next mounting I need a restart.

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