Qvm-usb attach quirkiness

User Support
1

Its probably me who is quirky. I’ve always had “problems” with attaching a USB SSD to my backup VM.

qubes 4.04
backup VM is debian
sys-usb is debian

I execute in Dom0

[user@dom0 ~]$ qvm-usb list
BACKEND:DEVID  DESCRIPTION                      USED BY
sys-usb:2-3    Logitech_USB_Receiver            
sys-usb:3-6    Samsung_PSSD_T7_S5TFNS0R524911K

Then
qvm-usb at backup sys-usb:3-6

Then

[user@dom0 ~]$ qvm-usb list
BACKEND:DEVID  DESCRIPTION                      USED BY
sys-usb:2-3    Logitech_USB_Receiver            
sys-usb:3-6    Samsung_PSSD_T7_S5TFNS0R524911K  backup

and my USB drive shows up in Nautilus in the backup VM. However if I execute an ls command on the usb drive I get the error below

user@backup:~$ ls /media/user/T7/QubesBackup
ls: cannot access '/media/user/T7/QubesBackup': No such file or directory

If I then go into Nautilus and click on T7 and then issue the ls command it works

user@backup:~$ ls /media/user/T7/QubesBackup
qubes-backup-2021-07-14T222757  qubes-backup-2021-07-21T175626
qubes-backup-2021-07-15T221701  qubes-backup-2021-07-24T215610
qubes-backup-2021-07-18T215145  qubes-backup-2021-07-28T201200
qubes-backup-2021-07-19T214522  qubes-backup-2021-08-04T071626
qubes-backup-2021-07-20T134452  qubes-backup-2021-08-07T174433
qubes-backup-2021-07-21T174806

This is repeatable. What is Nautilus doing that I am not?

Any pointers much appreciated.

Tried this approach

[user@dom0 ~]$ qvm-block
BACKEND:DEVID  DESCRIPTION   USED BY
backup:sda     PSSD_T7 ()    
backup:sda1    PSSD_T7 (T7)  

[user@dom0 ~]$ qvm-block at backup sys-usb:sda
qvm-block: error: backend vm 'sys-usb' doesn't expose device 'sda'
2

ok I needed to mount the USB SSD

run the mount command from dom0

qvm-usb at backup sys-usb:3-6
sleep 1
qvm-run --pass-io backup 'sudo mount /dev/sda1 mnt'
qvm-backup -y --profile usbback
qvm-run --pass-io backup 'ls $HOME/mnt/QubesBackup/* -t | head -1' | qvm-backup-restore -p passphrase.txt --verify-only -d backup $(head)
if [ $? -eq 0 ]
 then
   echo "USB verify ok"
else
  echo "USB verify error"
fi