file system issue with block device passthrough

[Azapa]

I just noticed something on my homelab server the other day, and while i am sure it is an issue, i don't know how much of an issue it might be.

i have an old lenovo minipci running proxmox ve 8 (pve-manager/8.4.19/a68fb383814bb1e6 (running kernel: 6.8.12-23-pve )to be exact)

it has an old usb external drive doing passthrough to one of the VM's and i noticed something weird the other day.

on the server itself, if i look at block devices (lsblk -f) i get this - sdc being the passthrough device:

sdc
└─sdc1 btrfs cb30a...

but if i log in to the vm itself and look at the device with the same command i get this:

sdc
└─sdc1 ext4 1.0 67ad....

i.e. the device has 2 issues:

1. why does the bare metal detect the drive as being BTRFS and the vm using it on passthrough detect it as being EXT4?
2. why does it have a different UUID?

i verified the fstab and the file system is indeed being mounted as ext4. i set this thing up with PVE 6 several years ago and don't remember exactly how i formatted everything... it was my first foray into proxmox and i followed a guide in the forum on setting up passthrough. i cant remember how i initially formatted the drive, or if i reformatted it when it went i got the pass through to work.

im not too concerned about the UUID thing as much as i am concerned about the file system thing. i am currently backing up the drive leaving it in place on the VM as to do my best to keep whatever is on it from getting corrupted in any way, then i plan on reformatting the drive so the file system matches in and out of the virtual environment.

am i right to be concerned here? maybe i dont understand the passthrough process as much as i thought but i am very interested in how this happened in the first place, tho i doubt i will ever figure that out.

 

[Neobin]

What does the VM config (qm config YourVMID) look like?

 

[fiona]

Hi,
are you sure this is the same device? Just because it has the same /dev/sdX letter, that doesn't mean anything if it's not the same machine.

 

[Azapa]

What does the VM config (qm config YourVMID) look like?

bios: ovmf
boot: order=scsi0;ide2;net0
cores: 2
efidisk0: local-lvm:vm-100-disk-1,efitype=4m,pre-enrolled-keys=1,size=4M
ide2: local:iso/debian-11.2.0-amd64-netinst.iso,media=cdrom
memory: 8192
meta: creation-qemu=6.1.0,ctime=1643079731
name: grape
net0: virtio=FE:B5:F0:1F:B9:26,bridge=vmbr0,firewall=1
numa: 0
onboot: 1
ostype: l26
scsi0: local-lvm:vm-100-disk-0,size=15G
scsi2: /dev/disk/by-id/usb-TO_Exter_nal_USB_3.0_2015033100081-0:0,backup=0,size=5723134M
scsihw: virtio-scsi-pci
smbios1: uuid=40dd359c-eaf3-415a-ba51-eb54bfdaa03b
sockets: 2
usb0: host=0080:a001
vcpus: 4
vga: virtio
vmgenid: 26ce93bc-1cff-4f8a-84c0-c1606f4946ab

 

[Azapa]

Hi,
are you sure this is the same device? Just because it has the same /dev/sdX letter, that doesn't mean anything if it's not the same machine.

there is only one external hard drive attached to the machine, so i dont know how it could be anything else.

i think the drive was originally a WD MYBook or something like that... the controller failed inside the original housing and i yanked the drive and put it into a different external enclosure. i had do update the UUID in the config file so it would keep passing though the drive, but it was pretty seamless from what i remember. that was about 2 years ago tho, so i can't remember if i needed to do anything else at the time.