FOR VIRTUAL MACHINE

In Proxmox terminal:

  ls -l /dev/disk/by-id/
  qm set abc -scsi1 /dev/disk/by-id/xxxxxxx

** where abc is the virtual machine
** where xxxxxx is the drive ID

Under Ubuntu, mount drive:

  lsblk                 <-- to list down the available drives
  mkdir /mnt/newdrive   <-- to create a folder that will be mounted on
  sudo mount /dev/sdx /mnt/newdrive/

to mount automatically on boot after first mount

  sudo blkid /dev/sdx1    <-- get the UUID of the new drive 
  sudo nano /etc/fstab    <-- edit the fstab and add line below
     UUID=YOUR_UUID_HERE /mnt/newdrive ntfs3 defaults,uid=1000,gid=1000,nofail 0 0
  sudo umount /mnt/win_share
  sudo mount -a
  
  *Note: uid=1000 and gid=1000 ensure your main Ubuntu user owns the files so you don't run into permission issues. nofail ensures that if you ever pull the physical drive out, the VM will still boot up normally.

FOR LXC MACHINE

In Proxmox terminal:

  mkdir -p /mnt/host_ntfs
  mount -t ntfs3 /dev/sdx1 /mnt/host_ntfs
  pct set xxx -mp0 /mnt/host_ntfs,mp=/mnt/container_ntfs