MPICH出错求助

ph19840216

两台虚拟机上的RHEL AS4U4 ，主机名分别为RHEL4A   RHEL4B
网络没问题，rsh 和ssh都配成无密码互相访问了，安装的mpich包是mpich2-1.0.5p4.tar.gz
./configure --prefix=/usr/local/mpi
make
make install也都正常

RHEL4A运行
mpd&
mpirun -np 2 cpi

Process 0 of 2 is on RHEL4A
Process 1 of 2 is on RHEL4A
pi is approximately 3.1415926544231318, Error is 0.0000000008333387
wall clock time = 0.007532

运行
mpirun -np 3 -host RHEL4A cpi

Process 2 of 3 is on RHEL4A
Process 1 of 3 is on RHEL4A
Process 0 of 3 is on RHEL4A
pi is approximately 3.1415926544231323, Error is 0.0000000008333392
wall clock time = 0.016403

(RHEL4B上运行以上两个也都正常)

再运行下面的就报错了，我在RHEL4A上执行
# mpirun -np 3 -host RHEL4B cpi

mpiexec: unable to start all procs; may have invalid machine names
    remaining specified hosts:
        10.0.10.203 (RHEL4B)

为什么A的mpich不能起B上的进程？

more /etc/hosts

127.0.0.1       localhost.localdomain   localhost
10.0.10.201     RHEL4A
10.0.10.203     RHEL4B


more /root/.rhosts
RHEL4B
RHEL4A

more /root/nodelist
RHEL4A
RHEL4B


请教在两台机器上执行mpich还需要特殊设置吗？