Hi,
There is a bug in the newest ISO file.
When I install OMV 2.1 ISO from a usb pendrive to another usb device (usb hdd), the grub information will be written to the source pendrive.
So, the OMV can not start if I remove source pendrive. I have to install grub with manual commands to the destination usb hdd to fix this bug.
Please, check ISO file.