[centos升级]正确的从CentOS 6升级到CentOS 7

引用

redhat-upgrade-tool --force --network 7.0 --instrepo http://centos.communilink.net/7.3.1611/os/x86_64/

使用--force选择，强制升级

参考： http://blog.hlogc.com/20160313/upgrade-from-centos-6-to-centos-7/


centos7下载地址： http://mirrors.gigenet.com/centos/7/isos/x86_64/
http://isoredirect.centos.org/centos/7/isos/x86_64/CentOS-7-x86_64-Everything-1611.iso