Some confusion about the "First Deadline Rule"

[Tom Smith]

 Hi everyone,

I am studying Chapter 19 "Rate Monotonic Manager"  of c_user.pdf, and I get
some questions

In c_user.pdf, it says

"For a given set of independent periodic tasks, if each task meets its
first deadline when all
tasks are started at the same time, then the deadlines will always be met
for any combination
of start times."

my question is that:
1. If a set of  independent periodic tasks do not meet the "Processor
Utilization Rule",  but they satisfy the "First Deadline Rule",  can they
be scheduled  using RMS ?

2. Is it necessary to start all tasks at the same time in a real
application, or  is it just a trick during analysis phase?

any review on this point from anyone is welcomed. So feel  free to  comment.
Best regards,

Tom Smith
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