Hi, I’m attaching my USB Devices to my qubes, they are shown in the qube and I can access files but I can’t move new files to my USB drives. It says there is no space left on my USB/ Memory Cards but there definitely is. Same issue with completely empty USBs.
What the issue here? It worked fine before but haven’t used USB drives in a while.
Maybe your USB device is NTFS- or HPFS/Apple-formatted?
Did you try to format the USB with ext2 or exFAT?
No, I did not try to format them because I have used them before without issues so that can’t be it. Those are my backup USBs to backup my qubes on. I have backed up several times before without any issues but now it says disk is 100% full.
Well. Hard to guess without logs or a better description of what you are doing.
Are you by any chance backing up through a qube/vm which has run out of disk? (guessing)
If they are all usb “key” or card devices, then it may be useful to look at the system journal of the usb qube at the moment you plug in the usb device.
Certain brands have firmware which marks the card as read-only after repeated write failures. A message then appears about “write protect” when the device is plugged in.
Some software gives a disk full error for a read-only device, although I am not sure about qubes-backup.
It can easily happen if the USB 5 volt supply is weak, or if a bad cable is used. Multiple simultaneous read and write activities seem to increase the risk. Thanks to this, I have a collection of expensive and unusable memory cards and keys - almost all are SanDisk branded, but others may be susceptible.
I make an backup and safe it to my qube called “backup” so it’s safed first in an qube. Works fine. Then I connect my USB pen drive and attach it to my “backup” qube to transfer the just backed up system to my USB stick. While the USB stick connects and I can read the files (including old back up files that I’ve transfered to the pen drive using the very same method), I can’t transfer the new backup file because it says my USB pen drive disk is full. Which is not true.
I have the same issue with an micro SD card.
Sys-usb is usually off, I only run it when I want to safe my backup file to my sd-card or to my pen drive.
Anyway, I solved it for now by using a new USB pen drive that works fine. I will eventually format the non-working devices and try using them again.
Thanks for trying to help here!
So, it actually says “No space left on device”?
Just checking, because @phceac is right. NAND flash does have a lifespan, and the more you write to it, the shorter its lifespan becomes.
You can only write to it so many times until its onboard firmware basically says “Nope. I’m failing. I’m now a read-only device to prevent any potential failures”.
And you said you’re backing up entire qubes onto these USB sticks, and qubes are big. A lot of writes there…
SD cards are notorious for this, because writing to them is done using different voltages. Kind of hard to explain in simple terms, but instead of having individual memory cells, SD flash has cells that respond differently to different voltages, meaning you can store more than a single bit in them. And quite a lot of SD card readers have crappy voltage regulators, which means file corruption can be more common that you might think…
Thus the lifespan cycles starts again 
Spare a thought for all the SSDs in a YouTube data centre. Oh, 'tis a hard life… 