yeah… no. I mean…
I don’t know when someone installs CentOS7 with a DVD Writer installed if the procedure automatically adds some packages for optical disk writing. And I don’t think that into goals for Nethesis about NethServer there was that kind of goal.
So… IMVHO more software is needed.
Several options might be also already part of the distro (or the included repositories), without taking risks for download single packages from unknown sources or add more unknown repositories.
I can get that you’d love “hey… I did it like this, write these commands yada yada yada blah blah blah, jargon jargon jargon and everything will be allright” but… as a matter of fact I never did it, because if i’d put a DVD-R drive into a server would be because i don’t have any other optical drive spare, not for burning ISO files. 
NethServer is not a desktop distro for newbies. NethServer should be a tool for sysadmins which would love to do other things. You’re still not a linux sysadmin? Me neither, welcome to the club.
However…
You can still:
- search pages
- write a list of console commands/packages
- verify if CentOS 7 already have one or more of them into repositories
- write the second list of possible options
- install one of them. Try it.
- works? Great! yooo hooo!!!
- doesn’t works for you? I’m sorry… uninstall it, write down why did not worked/you liked, than
- install the second one. Try it.
- rinse, wash, repeat
- if you find a good option for you… come back here to tell us your experience! I’d love to read that
Wish the best for your experience as wannabe-sysadmin!
https://community.nethserver.org/t/how-clone-hdd-for-nethserver/
In this experience i told how i cloned NethServer from one drive to another, might be useful for someone…