Most performant way to attach external drives to VMs

[Scepter]

Hi,

I'm planning to set up a Proxmox VM as backup server for my local devices. For that, I'd like to attach an USB 3.0 drive as additional storage.
After doing some research, I've found the following approaches:

• Use drive as Proxmox storage extension and create virtual drives on it
• Passthrough the entire USB device
• Attach a single partition directly to the VM via SCSI

So now I'm wondering what's the best in terms of stability and performance. Since Time Machine runs a backup every hour and everything can easily grow to a few gigabytes, getting the full performance out of the USB port without adding too much CPU overhead would be quite important for me.

Thanks!

 

[Dunuin]

option B (USB passthrough) is fully emulated, so not great for anything that needs good latency or throughput like a HDD.

Option 1 and 3 will both result in virtual disks seen by your VM (there is no way for your VM to see the real disk without PCI passthrough of a PCIe USB card).
But I would prefer option 3 (disk passthrough), as this makes it easier to attach that disk to another host in case of an emergency.

 

[Scepter]

Great, thanks a lot!