"Thomas F. O'Connell" <tfo@sitening.com> writes:
> A base backup taken from a running postmaster will still include a
> postmaster.pid file, which will prevent a new postmaster from being
> able to be started.
Usually not; only if the PID mentioned in the file belongs to an
existing process belonging to the postgres userid does Postgres believe
that the pidfile is valid.
It might be worth mentioning this as you suggest, but I think it's a
sufficiently low-probability case that your failure was probably due to
something else.
regards, tom lane