External Hard Drive unrecognized

Sometimes my pc no longer sees one of my USB 3.0 external hard drive.
It happens suddenly... The letter disappears from the list of external hard drives in the file explorer.
I found that there is one way to fix the situation using regedit:

- I go to
- I Remplace the value "EnableLUA" from "1" to "0" :
- I Reboot

My question is : why does the value revert back to 1 by itself? Why is this linked to my issue?
And is there a way I could avoid this, or have a program that I can double click to reset the value to 0 without opening regedit etc...

Jean-Christophe GALLANDKorea R&D DirectorAsked:
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The cable, cases interface or drive itself may be faulty.
Test these and replace as needed.

UBCD has drive makers diagnostic tests or download the free test from drive maker site. http://www.ultimatebootcd.com/download.html
Jean-Christophe GALLANDKorea R&D DirectorAuthor Commented:
The usb drive is a box commercial one (Seagate Back Up Plus) and I used the cable provided in the box. The cable would be the only easy thing to replace. However, it looks to me that the issue is more windows related than hardware. Indeed, most of the time this external drive just works well
check in the energy settings that the drive is not turned off by windows to save power
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Jean-Christophe GALLANDKorea R&D DirectorAuthor Commented:
The usb external drive is not powered by the USB but has its own separate power supply. Should I still modify the Windows power settings? If yes, which ones
If the external drive is HDD and spinning when Windows no longer sees it then it is probably nothing software related, and you do not need to modify the Windows power settings.

If you wish to check Windows power settings
Control Panel > Device Manager > USB Controller > Right click on the USB for the said USB 3.0 external hard drive > Properties > Power Management
Un-check the "Allow computer to turn off this device to save power"

Also on the USB 3.0 external hard drive case there may be a switch "Manual" (= always spins) / "Auto" (=only spins when data is being accessed )
Recommend " Manual" as stopping and starting a HDD wears it out at a faster pace than spinning it 24/7 (the power saved vs the life of the drive is not economical )

"Sometimes my pc no longer sees one of my USB 3.0 external hard drive."

Do you have another USB 3.0 external hard drive plugged into that still is seen by Windows while the other is not seen?
If this is the case then it is not a Windows issue, it is a hardware issue.
Test this by swapping the two USB 3.0 external hard drives USB ports.
If you can, please test the troublesome USB 3.0 external hard drive on another PC.

Other tests to try:
First make sure that you have no folders open or are not reading or writing data from / to the USB 3.0 external hard drive.
1. unplug the cable from the USB then plug it back in ... does Windows now see it?
2. unplug the power for the drive then plug it back in ... does Windows now see it?

You may have what is called "weak contacts" of the USB cable or ports.
Replace the cable, but if it is the ports then replacing the External USB drive case and the last port(s) to suspect is on the mother board.
You can test this out by swapping the External USB drive to another USB port.
Did you test the External USB drive with the manufactures diagnostic tools, as I posted before?
noxchoGlobal Support CoordinatorCommented:
My question is : why does the value revert back to 1 by itself? Why is this linked to my issue?
And is there a way I could avoid this, or have a program that I can double click to reset the value to 0 without opening regedit
This is caused by some program which you are using. Try to check when exactly does this start happening. The must be some logic.
tx for posting details Michael, but i thought the energy settings (from control panel) were known
weakcontacts would not reset registry settings imo
Jean-Christophe GALLANDKorea R&D DirectorAuthor Commented:
Thanks all
I did change the power setting just in case
My USB external is HDD not SSD. It is a commercial 8TB "Backup Plus Desktop Drive" from Seagate and has no manual switch.
When Windows no longer sees it, I still see the LED lit on it so it is still powered. When that happens, I look at the device manager in the configuration panel and I can see that the USB 3.0 bus controller has an issue (exclamation point). So I decide to reinstall the driver (Texas Instrument) but Windows refuses to run  the driver installation program unless I change the value "EnableLUA" from "1" to "0" in Regedit. I modify this value, reboots and the problem vanishes without even the need to reinstall the driver. But the problem comes back after a few days or weeks.
I have been unable to find a diagnostic tool on Seagate website. All I can find is a utility to backup data, modify performances but it does not seem to include a diagnostic tool.
noxchoGlobal Support CoordinatorCommented:
What is the exact model of your drive? Note, the Seatools work with internally connect drives. Means you would have to open the box and get the drive out.
Jean-Christophe GALLANDKorea R&D DirectorAuthor Commented:
As mentioned above, it is a  8TB "Backup Plus Desktop Drive" USB 3.0 from Seagate
noxchoGlobal Support CoordinatorCommented:
8TB? Then it is a RAID device and you cannot check it with a drive test utility. So have you checked when exactly the problem occurs? Are you running any kind of backup software at the moment or before the drive gets unmounted?
No way to get higher than 2.2TB on one volume on MBR, regardless of the OS, BIOS
Must use GPT to have one volume as 8TB
Jean-Christophe GALLANDKorea R&D DirectorAuthor Commented:
I have not yet linked the issue to any running program. The drive capacity is indeed 8TB and came formatted for windows when I bought it
noxchoGlobal Support CoordinatorCommented:
It is already GPT and preconfigured. I don' think it has what to do with the drive itself. If the registry key changes itself then something doing it. Just control it patiently and check when it does change.
I know a similar case when NoAutomount=0 key always changed to 1 after using third party backup tool.

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