环境：
# cat /etc/redhat-release Red Hat Enterprise Linux Server release 7.0 (Maipo) # uname -a Linux openstack.com 3.10.0-123.el7.x86_64 #1 SMP Mon May 5 11:16:57 EDT 2014 x86_64 x86_64 x86_64 GNU/Linux
硬盘2块：
sda:20GB ，sdb 20GB
原文：http://www.cnblogs.com/zydev/p/5783434.html