Check in the GUI the serial number of the HDD (navigation: Proxmox URL > Notes > Disks > copy Serial)

Check in the GUI the VM number (e.g. 107) (navigation: Proxmox URL > Virtual Machine >number and name of vm

Write it down

Used the shell of the node (navigation: Proxmox URL > node > Shell)

Used this command to navigate to the disk folder (by-id):

cd /dev/disk/by-id/

This to list the Disks (by-id)

ls

This comment to attach the disk to the vm. The 101 is the number of the vm and the numbers and letters behind by-id/ is the disk. The -scsi5 number could be anything. You could add more scsi disks in this way.

qm set 107 -scsi5 /dev/disk/by-id/ata-ST8000DM004-2CX188_WCT2Z8PX

If i was done (e.g. finised with my backup) then I used this comment:

qm unlink 107 --idlist scsi5

Automate the steps by this new script: SCRIPT LINK