Backup job fails with "A device which does not exist was specified."

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#1

I encounter a strange behaviour with my new SSD (external via USB 3.0). A backup command that worked before with a classic external hard drive produces errors now deep within the job (often after an hour or longer):

2023-07-13 20:25:41.752 ERROR CHUNK_MAKER Failed to read 0 bytes: read \\?\C:\ProgramData\.duplicacy-web\repositories\localhost\6\.duplicacy\shadow\MEDIA\iTunes-Ordner mit TV-Shows (DRM)\iTunes\iTunes Media\TV Shows\Breaking Bad\Season 5\01 Lebe frei oder stirb.m4v: A device which does not exist was specified.

2023-07-13 20:25:45.770 INFO VSS_DELETE The shadow copy has been successfully deleted
Failed to read 0 bytes: read \\?\C:\ProgramData\.duplicacy-web\repositories\localhost\6\.duplicacy\shadow\MEDIA\iTunes-Ordner mit TV-Shows (DRM)\iTunes\iTunes Media\TV Shows\Breaking Bad\Season 5\01 Lebe frei oder stirb.m4v: A device which does not exist was specified.

I’m not sure what happens. Seems like the drive had been (probably very briefly) disconnected from the PC? When I check the drive is (back?) there.I tried also without VSS to no avail.

The SSD is an SAMSUNG T7 secured by a password application.

I guess it’s an USB problem unrelated to Duplicacy but you never know (something with folder and/or file names or any other weird thing?).

Maybe someone has an idea what happens here. I couldn’t identify any USB culprit yet, be it a device or an associated driver.

I checked in an USB Logger to see if there was any unplug operation: Sometimes there was, but the error shows up even without any unplug event.

Thanks for any help!

#2

The “password application” would be my first suspect. They are invariably unstable garbage. Try reformatting the disk without it and see if the issue goes away. If you indeed need full disk encryption you can explore other options — like veracrypt or bitlocker.

I would be also suspicious of VSS; it is fragile and running chldsk often helps fix issues with it— but since you are seeing it even without — there must be something else involved.

#3

Thanks for your suggestions!

I’m trying a lot of things so far: Using the SSD without Samsung password-protection, w/o VSS, w/o threads.

chkdsk seems okay.

So far the occasionally unplugging still occurs, but sometimes the error comes w/o unplug events. I also hear the system sounds from USB unplugging/plugging events although the USB Logger does not detect any such events. Strange.

Right now testing w/o (until then still installed) Samsung software.

Still on the list: Formatting, using other USB ports (again). But then I’m running out of ideas … :slight_smile:

#4

I have a similar problem with a Samsung SSD drive attached to my Mac. It would show up, then eject, and sometimes would get a warning it was corrupted. File copy would fail.

I changed the cable and all was fine after that.

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#5

Good tip, thanks!

I tried another cable and it seems fine for the moment. I used the original Samsung cable though, what a disappointment …

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#6

Great catch @phillipmcmahon!

I’m using a few Samsung external SSDs -T5 and T7 and don’t even take the included cables out of the box. They go straight to trash along with their silly warranty booklets and pouches. Not just with these products; just as matter of policy. The included cables are the cheapest and crappiest manufacturer could source from China in bulk that can’t be sold separately because they are so horrible. It’s so weird to penny pinch on accessories that undermine performance of the actual produc, let alone _storage device holding customer data — but I guess money is money.

Instead, I recommend using short thunderbolt 3 (or 4) cables (Anker or Belkin sell some decent ones). Thunderbolt is by necessity held to higher quality standards than USB. Short cables don’t have any repeaters inside, there are just wires, and therefore work for USB.

#7

Agree, it’s weird they cheap out on the cables when that’s a rather critical part of their pretty decent SSDs working well.

100% agree on going the Thunderbolt cable route. I now use v4 cables for all my USB-C interface components. Never had an issue since.

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#8

I’ve got a Windows PC with USB 3.0 so I guess I go for decent USB cables.

#9

They will still work, mechanically and electrically they have the same interface. TB3/4 cables have higher requirements so will always be a safer bet.