虚拟机恢复快照后，使用yum安装软件，提示下面的信息，开始以为是yum源的问题或者DNS的问题，但是无果，最后再看一下服务器的时间，坑了，还原快照，时间变成以前的了。
[root@localhost yum.repos.d]# yum install lrzsz -y 已加载插件：fastestmirror Loading mirror speeds from cached hostfile One of the configured repositories failed (未知), and yum doesn't have enough cached data to continue. At this point the only safe thing yum can do is fail. There are a few ways to work "fix" this: 1. Contact the upstream for the repository and get them to fix the problem. 2. Reconfigure the baseurl/etc. for the repository, to point to a working upstream. This is most often useful if you are using a newer distribution release than is supported by the repository (and the packages for the previous distribution release still work). 3. Run the command with the repository temporarily disabled yum --disablerepo=<repoid> ... 4. Disable the repository permanently, so yum won't use it by default. Yum will then just ignore the repository until you permanently enable it again or use --enablerepo for temporary usage: yum-config-manager --disable <repoid> or subscription-manager repos --disable=<repoid> 5. Configure the failing repository to be skipped, if it is unavailable. Note that yum will try to contact the repo. when it runs most commands, so will have to try and fail each time (and thus. yum will be be much slower). If it is a very temporary problem though, this is often a nice compromise: yum-config-manager --save --setopt=<repoid>.skip_if_unavailable=true Cannot retrieve metalink for repository: epel/x86_64. Please verify its path and try again [root@localhost yum.repos.d]#
修改时间的界面
再yum
看结果就正常了。