Eric Smith <eric_h_smith(at)mac(dot)com> writes:
> Yes, if I start one, but not the other, the process works just great.
> It's only when trying to run both that I have a problem.
Have you looked into the postmaster logfile?
One likely idea is that you don't have shmall cranked up high enough
for two servers, which'd result in something like
FATAL: could not create shared memory segment: Cannot allocate memory
in the postmaster log.
regards, tom lane