Understanding the Need to Leave the Debian .iso in Place

[dtheese]

I am running the following Proxmox version:
pve-manager/5.1-46/ae8241d4 (running kernel: 4.13.16-1-pve)

I have created VMs from the following Debian iso, stored in the following location:
/var/lib/vz/template/debian-8.7.1-amd64-DVD-1.iso

After creating the VMs, configuring them, maintaining them (including upgrading them from Debian 8 to Debian 9), and running them for months, I tried removing the .iso listed above to free up space. I figured the initial install image was no longer needed. The VMs continued running, but the first time I tried to reboot them, they would not come up until I put the .iso back in place.

Why must I leave the Debian installation .iso in place after fully installing Debian on a VM?

 

[mbaldini]

Remove the cdrom line in the VM configuration that maps to the installation iso. In that way the VM can start even if you deleted the ISO.