centos4.7 yum出错
安装完centOs4.7 IA64
然后yum update更新，出错：
"Setting up Update Process
Setting up repositories
not using ftp, http[s], or file for repos, skipping - 4 is not a valid release or hasnt been released yet
Cannot find a valid baseurl for repo: update
Error: Cannot find a valid baseurl for repo: update"
原因：yum源不可访问
解决方案：下载可用的源 http://vault.centos.org/4.9/CentOS-Base.repo
然后 替换/etc/yum.repos.d/CentOS-Base.repo
