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External hard drives don't show up in El Capitan: UNRESOLVED

I've always used my external HD "WD my book" on my imac. I have El Capitan and have had no issues.
But yesterday I plugged my WD external HD into my PC to transfer some pictures. PC never recognized it so I reconnected back to my mac and neither my mac would recognized it. It gave me this message.
upload_2016-10-3_23-32-5.png


I tried the Disk Utility and no option to mount, here is the info

upload_2016-10-3_23-25-38.png


Device Identifier: disk1
Device Node: /dev/disk1
Whole: Yes
Part of Whole: disk1
Device / Media Name: 10EAVS External
Volume Name: Not applicable (no file system)
Mounted: Not applicable (no file system)
File System: None
Content (IOContent): None
OS Can Be Installed: No
Media Type: Generic
Protocol: USB
SMART Status: Not Supported
Total Size: 1.0 TB (1000204886016 Bytes) (exactly 1953525168 512-Byte-Units)
Volume Free Space: Not applicable (no file system)
Device Block Size: 512 Bytes
Read-Only Media: No
Read-Only Volume: Not applicable (no file system)
Device Location: External
Removable Media: No
Virtual: No
OS 9 Drivers: No
Low Level Format: Not supported


How do I access it? I tried the some of the fixes suggested here except the ones about purchasing software.
I used the free mac data recovery mac and the info, the files are there but I dont want to pay for a software if I can use another disk utility to repair it and access it.

I've seen a couple of user had this exact same issue but it does not seem it was resolved for them.

any solutions?
thanks,
 
gerarddezeeuw said:
I asked Apple. They suggested an 'smc reset'. Switch off your computer. Remove all peripherals, including keyboard, screens and power cable. Push the power button for 5 seconds (note: when there is no power!). Switch on: my hard disks appeared!
Click to expand...

Thank you who ever wrote this. I have spent days and so many hours trying to fix this. Tried command, option shift and power button which got my hard disk back on but not my dvd writer. Then tried the above approach now all is working! Yay!
 
I'm confused. On a 2007 Mac Pro tower, How do you "switch on" the computer? By plugging the power cord back in while still holding down the power button on the front of the case? Please explain. Thank you.
 
Thanks for the instructions link. Unfortunately, that did not solve my problem. USB drives still not mounting in El Capitan. USB sticks and USB DVD drive mount fine though. I'm running on a "pikified" 2007 Mac Pro 2,1, upgraded from Yosemite. Didn't have the USB drives issue in Yosemite.
 
This is a very odd occurrence. I have exactly the same computer running ElCap upgraded from Yosemite, work A-OK.

Could you please issue the following in the Terminal:

Code: 
nvram -xp

?
 
hwojtek said:
This is a very odd occurrence. I have exactly the same computer running ElCap upgraded from Yosemite, work A-OK.

Could you please issue the following in the Terminal:

Code: 
nvram -xp

?
Click to expand...


<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">

<plist version="1.0">

<dict>

<key>IdlePML4</key>

<data>

0AovGID///8=

</data>

<key>SystemAudioVolume</key>

<data>

OA==

</data>

<key>SystemAudioVolumeDB</key>

<data>

+A==

</data>

<key>csr-active-config</key>

<data>

EAAAAA==

</data>

<key>fmm-computer-name</key>

<data>

Um9kbmV54oCZcyBNYWMgUHJv

</data>

</dict>

</plist>
 
hwojtek said:
Nothing unusal here. Perhaps you'd have more luck using this tutorial? https://appletoolbox.com/2017/03/mac-macbook-doesnt-recognize-external-drives-troubleshooting-tips/ (this applies not only to macbooks)
Click to expand...

Thanks, I will try those suggestions. I still think the issue, though, lies with El Capitan. As I said, my USB drives (all USB 2.0) worked fine under Yosemite. My Time Machine is on one such drive, and now Disk Utility reports there may be a partition problem with the drive. However, Micromat TechTool Pro reports no such problem. Since I can't even get the drive to mount, I may have to reformat the drive on my PC laptop (assuming it can detect and mount the drive) then see if the partition issue is resolved. I'll report my findings soon. Thanks again for your help.
 
Just a sec.
Could you please connect and power up all the drives in question and after some 10-20 seconds fire up the Terminal and enter
Code: 
diskutil list
?
 
hwojtek said:
Just a sec.
Could you please connect and power up all the drives in question and after some 10-20 seconds fire up the Terminal and enter
Code: 
diskutil list
?
Click to expand...

Here is the readout. Note my 500GB Time Machine USB drive is not in the list. it's icon is also not showing on the desktop.
 

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OK. I've read about an issue of disks not being shown in GUI apps, but them being available in Terminal. Seems it's just not the case, as there are none.

Do you have any other Mac available to plug the disk in and check if it's recognized?
 
I have a friend with a MacBook Pro who may be able to help me. If his computer, which is running High Sierra, can mount/read my USB drive, then it will confirm the El Capitan problem.
 
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hwojtek said:
OK. I've read about an issue of disks not being shown in GUI apps, but them being available in Terminal. Seems it's just not the case, as there are none.

Do you have any other Mac available to plug the disk in and check if it's recognized?
Click to expand...

Not sure if this will help diagnose the problem, but my Time Machine USB drive (Seagate FreeAgent GoFlex) is listed under System Information. However, the drive still will not mount in El Capitan.
 

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  • System Information USB Info.png
    System Information USB Info.png
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FWIW it seems you have lost the partition. I have no idea why, but I bet $5 it would work flawlessly if you clicked this dreadful "initialize" button (and lost your data on the external disk in the process).
It's just close to impossible that your fairly standard configuration (I have almost the same computer with ElCap on it) would trigger an issue that is "ElCap-specific". Either it's something screwed with this particular install (which would not indicate a problem with ElCap per se) or there is something screwed with this particular computer (ditto).

This is a tough one though, I admit.
 
hwojtek said:
FWIW it seems you have lost the partition. I have no idea why, but I bet $5 it would work flawlessly if you clicked this dreadful "initialize" button (and lost your data on the external disk in the process).
It's just close to impossible that your fairly standard configuration (I have almost the same computer with ElCap on it) would trigger an issue that is "ElCap-specific". Either it's something screwed with this particular install (which would not indicate a problem with ElCap per se) or there is something screwed with this particular computer (ditto).

This is a tough one though, I admit.
Click to expand...

When I first installed El Capitan, my external USB drives worked fine. At that time, I still had my Yosemite drive installed in the Mac Pro. It seems my problems started after I reformatted the Yosemite drive, to free up space to store my various user files. Is it possible the USB drives were still accessing files from the Yosemite drive even though I was booted into El Capitan? Note I installed El Capitan on a separate SSD, but did have to start the El Cap installation while running Yosemite.
 
OK, so I finally got my Time Machine USB drive connected to my friend's MacBook Pro. Long story short, his computer showed the Time Machine partiition as corrupted. The EFI partition was fine. He reformatted the Time Machine partition, which then made the entire disk readable again. When I plugged the drive back into my Mac Pro, it didn't immediately mount, but using the Mountain app I mentioned in a previous post, I was able to mount the drive. I have now successfully backed up my computer to this Time Machine drive. And (knock on wood) it's not unmounting unexpectedly. I assume it was the previous improper ejections of the disk that caused it to become corrupted.
 
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SG- said:
from the release notes:

Known Issues

  • USB storage devices, including internal SD card readers, may become unavailable after system sleep and require either re-plug or restart to recover.
  • USB input devices may become non-functional on some Macs after several days.
  • USB 1.0, 1.1 and older 2.0 devices may not function.
Click to expand...


Oh, well. Just those? Everything's fine, then!
[doublepost=1518838491][/doublepost]
NJM2323 said:
I'm having this problem--this forum doesn't have any answers I guess.
Click to expand...

In my situation, the external hard drives are not being seen AT ALL (even by diskutil). Yet, it isn't the USB ports because both my phone (tethered for internet access) and a thumb drive are working fine. Also, the issue isn't the cables unless suddenly three different cables on three different drives suddenly went bad while in warm, dry storage on my desk, away from EMT interference.

The weird thing is that just this morning, this problem wasn't--everything worked fine. I plugged in an external drive and it showed up fine.

But now... this.
 
Last edited:
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