The CDROM image was a firmware upgrade image from Dell (based on Linux). Mounting the image with iDRAC, it worked nicely. As one of the Servers had a dying iDRAC (Dell R320), I needed an USB stick.

I have used in the past the Smart Boot manager to boot into my machine that has multiple configurations (windows, linux etc). This works the best for me since I hate overwriting the MBR with Grub as ...