选项 1

首先尝试清除所有 yum 缓存：

# yum clean all
# rm -rf /var/cache/yum/*
# yum repolist

解决方案

yum 服务器包含元数据和元数据校验和。
下载元数据和校验和后，yum 客户端会比较两者以确保它们一致。
元数据缓存应该有问题，这会导致 yum 尝试下载最新元数据的错误。

选项 2

清理元数据：

# yum clean metadata

选项 3

编辑文件 /etc/yum.conf 并添加一行“http_caching=packages”，如下所示：

# vi /etc/yum.conf
[main]
cachedir=/var/cache/yum/$basearch/$releasever
keepcache=0
debuglevel=2
logfile=/var/log/yum.log
exactarch=1
obsoletes=1
gpgcheck=1
plugins=1
installonly_limit=3
http_caching=packages
# This is the default, if you make this bigger yum won't see if the metadata
# is newer on the remote and so you'll "gain" the bandwidth of not having to
# download the new metadata and "pay" for it by yum not having correct
# information.
# It is esp. important, to have correct metadata, for distributions like
# Fedora which don't keep old packages around. If you don't like this checking
# interupting your command line usage, it's much better to have something
# bananaally check the metadata once an hour (yum-updatesd will do this).
# metadata_expire=90m
# PUT YOUR REPOS HERE OR IN separate files named file.repo
# in /etc/yum.repos.d

1. 等待http缓存超时。

2. 为每个文件发出一个带有 no-cache 选项的 'wget'：

# wget --no-cache http://public-yum.oracle.com/repo/OracleLinux/OL6/latest/x86_64/repodata/primary.xml.gz

3. 临时配置 yum 不使用缓存版本的文件。
   编辑 /etc/yum.conf，并添加以下行：

http_caching=none

问题

场景一：

用户无法执行“yum install oracle-rdbms-server-11gR2-preinstall”。

yum 尝试下载最新的元数据（“http://public-yum.oracle.com/repo/OracleLinux/OL6/latest/x86_64/repodata/primary.xml.gz”）并拒绝它并显示错误消息“[ Errno -1] 元数据文件与校验和不匹配”。
在此之后，yum 会尝试遇到相同错误的下一个镜像并转到下一个镜像，依此类推，直到它尝试了所有镜像并以错误“没有更多的镜像要尝试”结束。

# yum install oracle-rdbms-server-11gR2-preinstall
Loaded plugins: refresh-packagekit, security
ol6_UEK_base | 951 B 00:00
ol6_UEK_base/primary | 686 kB 00:09
ol6_UEK_base 29/29
ol6_UEK_latest | 1.2 kB 00:00
ol6_ga_base | 1.1 kB 00:00
ol6_ga_base/primary | 2.9 MB 00:34
ol6_ga_base 8029/8029
ol6_latest | 1.4 kB 00:00
ol6_latest/primary | 22 MB 04:48
http://public-yum.oracle.com/repo/OracleLinux/OL6/latest/x86_64/repodata/primary.xml.gz: [Errno -1] Metadata file does not match checksum
Trying other mirror.
ol6_latest/primary | 22 MB 04:42
http://public-yum.oracle.com/repo/OracleLinux/OL6/latest/x86_64/repodata/primary.xml.gz: [Errno -1] Metadata file does not match checksum
Trying other mirror.
Error: failure: repodata/primary.xml.gz from ol6_latest: [Errno 256] No more mirrors to try.

场景2：

运行 uln_mirror 脚本也失败，错误是“Metadata File Does Not Match Checksum 元数据文件与校验和不匹配”

#/usr/bin/uln-yum-mirror
--snip-
rhnplugin.py:410:_getFile:RepoError: failed to retrieve repodata/update=einfo.xml.gz from ol6_x86_64_latest
error was [Errno -1] Metadata file does not match checksum :
Traceback (most recent call last):
File "/usr/bin/reposync", line 352, in 
main()
File "/usr/bin/reposync", line 256, in main
resultfile =3D repo.retrieveMD(ftype)
File "/usr/lib/python2.6/site-packages/yum/yumRepo.py", line 1571, i=n retrieveMD : return self._retrieveMD(mdtype)
File "/usr/lib/python2.6/site-packages/yum/yumRepo.py", line 1654, i=n _retrieveMD : size=3Dthisdata.size)
File "/usr/share/yum-plugins/rhnplugin.py", line 410, in _getFile : self.id, e)
RepoError: failed to retrieve repodata/updateinfo.xml.gz from ol6_x86_= 64_latest :error was [Errno -1] Metadata file does not match checksum