This issue is tricky because you need to know XenServer very well and understand the error message bellow while trying to launch a VM. The VM Needs storage that cannot be seen from that host I attached a CIFS with all ISOs files I needed to the XenServer and the machine where the ISOs where failled. With this message I had to understand the VM didn't want to boot because one ISOs was mounted in the virtual DVD drive and this ISOs wasn't available any more... I just had to empty the VM's virtual DVD drive and everything came back to normal. I am looking for a command line to empty virtual CD / DVD, if anyone have it, feel free to comment !