Computer "forgets" backup drive is attached

I have this problem with my Windows 10 machine since recent updates, but it's happening to my Windows 7 machine too, recently. I'm tired of asking questions on TenForums because no one answers, so I'll ask here.


Specific to Windows 7, when I run backup, I plug in an external enclosure with a 2 TB WD 3.5 inch drive in it into a USB port. The drive works fine and I know it because I took it out of a working computer. What happens is that during the backup, the drive goes offline and the backup fails. You can't even find the drive in Explorer.


Obviously, something isn't right. Anyone else had this problem?

Hi Mellon Head,

Have you checked that the USB port is functioning correctly and not damaged (i.e. not loose and subject to vibration and movement)?
Have you tried plugging the external enclosure into another USB port?
Do you have the same problem when plugging in a USB stick and using it (i.e. accessing, copying, moving, saving files etc)?
I assume that there is enough space on the external drive to complete the backup?
Could it be a problem with the external enclosure?
One other suggestion, does the screen saver (if you have one) kick in during the backup process?

I hope this helps!

Hi Mellon Head,

iko22 said:

Say, if you were to leave the External USB drive connected, without starting up the backup procedure, does the device go offline then?

Good point iko22.

One other suggestion.
If you use another 3.5 inch drive in the external enclosure does it work?
If it does, then you know that it is the drive, if it doesn't then you know that it is the enclosure, or a faulty port maybe.

I hope this helps!

There is a standard setting in both windows 10 and 7 that shuts off the hard disk after a set time to save power, it is supposed to work on non activity but some drives give "funny" telemetry to the OS and in the confusion power is switched off - There are controls in the power settings to control the timings, or best of all, completely switch off the power save option for the drives. This can also be due in correctly functioning drives where the backup system works for a time compressing files and then dumps the compressed container to the drive, if the processing exceeds to drive shutdown setting the power is correctly switched off as the drive is not in use

As this is also a USB connected Device there is a similar setting relating to all USB connections, this is I think accessible from the Device Manager, and you can switch off the power save on just the part of the tree involved (I find it easier if you display the Device Tree by connection rather than device

Sorry it's taken so long to get back to you guys. I've been out of town.


I found the settings that Nigel is talking about and I'm going to try those first. They were set to shut down the USB port after a while to save power.


I'll try it out tonight and get back to you.

Well, it didn't work. Halfway through the backup the drive disconnected again. I got this error in Device Manager:





I must admit that I'm confused at this point.

iko22 said:

Say, if you were to leave the External USB drive connected, without starting up the backup procedure, does the device go offline then?

Yes, it does go offline.

Paul Black said:

If you use another 3.5 inch drive in the external enclosure does it work?
If it does, then you know that it is the drive, if it doesn't then you know that it is the enclosure, or a faulty port maybe.

I have tried a second drive in the enclosure. Both drives exhibit the same issue, yet both work fine inside a computer.


I'm starting to wonder if I have a bad external enclosure.

Ok. Fixed. The USB3 port that I was using is faulty. USB2 works just fine.