Unable to attach an external SSD to an AppVM

User Support General
1

Hey folks,

I used for a long time 4.2.1, 4.2.2, 4.2.3 but after these I used for a few months Ubuntu. Well… Ubuntu is not a solution for what I need so I came back to Qubes, 4.2.4 this time.

I have a problem though. I want to put some of my backup on an AppVM called Vault but I have problems in attaching the external SSD. The manifestation was different but now I got only 1 error.
I am using the top-right icon ti attach/detach devices (I have separate sys-usb).

  1. First manifestation was to actually not attaching anything even though the device was looking attached to the desired AppVM.
  2. Second manifestation now is that I get a notification saying:
    error: qubesException - Device attach failed: Failed to add inotify watch for /run/udev: No space left on device.

Below are the lines from logs that appear after I try to attach the device.

[2025-07-16 08:56:47] [  583.855847] vhci_hcd vhci_hcd.0: pdev(0) rhport(0) sockfd(0)
[2025-07-16 08:56:47] [  583.855865] vhci_hcd vhci_hcd.0: devid(196610) speed(5) speed_str(super-speed)
[2025-07-16 08:56:47] [  583.855893] vhci_hcd vhci_hcd.0: Device attached
[2025-07-16 08:56:47] [  584.090742] usb 2-1: SetAddress Request (5) to port 0
[2025-07-16 08:56:47] [  584.090758] usb 2-1: new SuperSpeed USB device number 5 using vhci_hcd
[2025-07-16 08:56:47] [  584.112457] usb 2-1: New USB device found, idVendor=04e8, idProduct=61f5, bcdDevice= 1.00
[2025-07-16 08:56:47] [  584.112490] usb 2-1: New USB device strings: Mfr=2, Product=3, SerialNumber=1
[2025-07-16 08:56:47] [  584.112506] usb 2-1: Product: Portable SSD T5
[2025-07-16 08:56:47] [  584.112518] usb 2-1: Manufacturer: Samsung
[2025-07-16 08:56:47] [  584.112526] usb 2-1: SerialNumber: 12345686BF26
[2025-07-16 08:56:47] [  584.129086] usb 2-1: USB controller vhci_hcd.0 does not support streams, which are required by the UAS driver.
[2025-07-16 08:56:47] [  584.129128] usb 2-1: Please try an other USB controller if you wish to use UAS.
[2025-07-16 08:56:47] [  584.129154] usb-storage 2-1:1.0: USB Mass Storage device detected
[2025-07-16 08:56:47] [  584.129664] scsi host0: usb-storage 2-1:1.0
[2025-07-16 08:56:47] [  584.264554] vhci_hcd: connection closed
[2025-07-16 08:56:47] [  584.264584] vhci_hcd: stop threads
[2025-07-16 08:56:47] [  584.264601] vhci_hcd: release socket
[2025-07-16 08:56:47] [  584.264609] vhci_hcd: disconnect device
[2025-07-16 08:56:47] [  584.264686] usb 2-1: USB disconnect, device number 5

How do you attach external thumb drives? Now I see that in the USB icon (top-right) the storage devices appear on another section called “Data (Block)) Devices”. Where shall I try to add the device, from this section or the below section?

2

If you just need to read or write data to a partition the safest option is to attach just that partition’s device to the VM.

If you need to, for example, repartition the disk you will need to attach the disk block device to the VM.

On the other hand, attaching the usb device (instead of the block devices) to the VM is the riskier option.

This is explained here.

3

It seems like the entries (usb device and the partition) disappear immediately from the "Data (Block) Devices) section after I click on detach and the only entry for this usb storage is on USB Devices section.
For example, I try to attach it from Data(Block) (it doesn’t matter if it works or not in the AppVM), after I detach it, disappears and I can’t see it issuing qvm-block.

Most of the times, when I try to attach the device from “Data(Block)” section is not added properly or it doesn’t appear on the AppVM. It works better when I try to add it from the USB Devices section.