安裝Fedora 15 後發現一個問題，就是yum 安裝時候老是出現HTTP Error 404等問題，看：
[[email protected] yum.repos.d]# yum search openssh
Loaded plugins: langpacks, presto, refresh-packagekit
http://repos.fedorapeople.org/repos/spot/firefox4/fedora-15/i386/repodata/repomd.xml: [Errno 14] HTTP Error 404 - Not Found : http://repos.fedorapeople.org/repos/spot/firefox4/fedora-15/i386/repodata/repomd.xml
Trying other mirror.
http://repos.fedorapeople.org/repos/spot/firefox4/fedora-15/i386/repodata/repomd.xml: [Errno 14] HTTP Error 404 - Not Found : http://repos.fedorapeople.org/repos/spot/firefox4/fedora-15/i386/repodata/repomd.xml
Trying other mirror.
Error: Cannot retrieve repository metadata (repomd.xml) for repository: fedora-firefox4. Please verify its path and try again
然後我索性把全部源給更換掉，找到了一些教育網的源，如上海交大的。
為了以防萬一，我先備份原來的源：
[[email protected] etc]# mkdir yum.repo.bak[[email protected] etc]# mv yum.repos.d/* yum.repo.bak/
新建一個源文件*.repo
[[email protected] yum.repos.d]# vim sjtu.repo
粘貼一下內容：
[Fedora-ftp.sjtu.edu.cn]
name=Fedora 15 - i386
baseurl=http://ftp.sjtu.edu.cn/fedora/linux/releases/15/Fedora/i386/os/
enabled=1
gpgcheck=0
gpgkey=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 - i386
baseurl=http://ftp.sjtu.edu.cn/fedora/linux/releases/14/Everything/i386/os/
enabled=1
gpgcheck=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-Fedora file:///etc/pki/rpm-gpg/RPM-GPG-KEY
[updates-ftp.sjtu.edu.cn]
name=Fedora updates
baseurl=http://ftp.sjtu.edu.cn/fedora/linux/updates/15/i386/
enabled=1
gpgcheck=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-Fedora file:///etc/pki/rpm-gpg/RPM-GPG-KEY
保存退出後，執行源更新命令就ok了
[[email protected] yum.repos.d]# yum update
更新速度很給力，達到4，5M/s
