"Must run" depend on you needs. For example, I consider cron
a must-have because otherwise I will not have log file rotation. And periodic updates check.
But if you don't even want logs, and plan to check updates manually, your case is different.
So basically the only correct answer is "it depends". Depends on how you want your system behave and on your use case.
Try to disable services one by one (see @muru comment though --- do not rename the upstart files, add a file with .override
extension with just the manual
command in it) and see if the system works for you. Or ask specifically what a service is doing (after researching a bit) and which are the effects of disabling it.
BTW, before doing it, be sure to know how to undo things without a graphic interface using recovery mode; the basics are well explained in How do I reset a lost administrative password?
.conf
file, but create a.override
file containingmanual
.