[CentOS] Cemtos 7 : Systemd alternatives ?

And more to the point, /usr isn't supposed t be needed until you are
past the point of mounting all filesystems so you can boot from
something tiny.  Doesn't modprobe need its files earlier than that?

>> I think that a lot of these objections are addressed here:
>>
>> http://www.freedesktop.org/wiki/Software/systemd/separate-usr-is-broken/
> Great. And it's from freedesktop... as opposed to, say, a system user, and
> which implies to me that it's for runlevel 5 GUI-only users....
>
perhaps you should read links before you make assumptions. 
and doubly so before you start following up.