由于CentOS6的系统安装了epel-release-latest-7.noarch.rpm 导致在使用yum命令时出现Error: xz compression not available问题。

解决方法：

1.到http://www.landui.com/Linux/fedora/epel/下载epel-release-latest-6.noarch.rpm

2.卸载epel-release-latest-7.noarch.rpm：yum remove epel-release

3.清空epel目录：rm -rf /var/cache/yum/x86_64/6/epel/

4.安装epel6:rpm -ivh epel-release-latest-6.noarch.rpm