USB disk on multiple VMs

[EllyMae]

I must have missed something in the documentation. Question: What happens when I allocate the same USB disk drive to multiple VMs? The GUI lets me do it. I'm wondering if that is something that should be done. It might be a way to get shared FS space if it's supported.

In case it matters, it has one partition, and it's formatted with XFS.

Thanks,

 

[Dunuin]

It might be a way to get shared FS space if it's supported.

No. When mounting the same block device at the same time in multiple systems you will corrupt the data on it. If you want to share data on it between VMs, mount it only at one place and then share it with NFS/SMB.

 

[EllyMae]

That makes sense. I come from the mainframe days, when they had stupid-simple file systems. But they did have ways to share disks between multiple systems.

I think the Proxmox GUI should prevent this from happening.

 

[Dunuin]

There are clustered file systems that support this, but PVE isn't directly supporting any of them (and I think they are all commercial...you can even spend hunded thousands on licenses...). And xfs is definitely not capable of that.

 

[LnxBil]

What happens when I allocate the same USB disk drive to multiple VMs?

That depends on what you want to archieve und how you did it.

Do you mean disk-passthrough or usb passthrough? The latter should not work via the GUI and makes no sense from a virtual hardware point of view IFF multiple VMs run at the same time.

 

[leesteken]

What happens when I allocate the same USB disk drive to multiple VMs?

This is typically a scenario that you cannot do with physical hardware (with common adapters, you could solder multiple USB plugs together yourself). Any existing adapters/switches/hubs will only allow the USB device to be used by one computer at a time. Any operating system inside the VMs are therefore not designed to handle this situation and it usually ends up in tears.