安装Fedora 15 后发现一个问题，就是yum 安装时候老是出现HTTP Error 404等问题，看：
[root@ yum.repos.d]# yum search opensshLoaded plugins: langpacks, presto, refresh-packagekit: [Errno 14] HTTP Error 404 – Not Found : Trying other mirror.: [Errno 14] HTTP Error 404 – Not Found : Trying other mirror.Error: Cannot retrieve repository metadata (repomd.xml) for repository: fedora-firefox4. Please verify its path and try again
然后我索性把全部源给更换掉，，找到了一些教育网的源，如上海交大的。
为了以防万一，我先备份原来的源：
[root@ etc]# mkdir yum.repo.bak[root@ etc]# mv yum.repos.d/* yum.repo.bak/
新建一个源文件*.repo
[root@ yum.repos.d]# vim sjtu.repo粘贴一下内容：
[Fedora-ftp.sjtu.edu.cn]name=Fedora 15 – i386baseurl=http://ftp.sjtu.edu.cn/fedora/linux/releases/15/Fedora/i386/os/enabled=1gpgcheck=0gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-Fedora file:///etc/pki/rpm-gpg/RPM-GPG-KEY[Everything-ftp.sjtu.edu.cn]name=Everything 15 – i386baseurl=http://ftp.sjtu.edu.cn/fedora/linux/releases/14/Everything/i386/os/enabled=1gpgcheck=0gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-Fedora file:///etc/pki/rpm-gpg/RPM-GPG-KEY[updates-ftp.sjtu.edu.cn]name=Fedora updatesbaseurl=http://ftp.sjtu.edu.cn/fedora/linux/updates/15/i386/enabled=1gpgcheck=0gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-Fedora file:///etc/pki/rpm-gpg/RPM-GPG-KEY
保存退出后，执行源更新命令就ok了
[root@ yum.repos.d]# yum update
更新速度很给力，达到4，5M/s
最大的成功在于最大的付出。
