我使用的是 512MB RAM 的 VPS。尝试一下yum -y update，这就是我得到的：
[root@cs09-prod ~]# yum -y update
Loaded plugins: fastestmirror, langpacks
Loading mirror speeds from cached hostfile
* base: mirror.sesp.northwestern.edu
* epel: mirror.steadfast.net
* extras: linux.cc.lehigh.edu
* updates: mirror.team-cymru.org
Resolving Dependencies
--> Running transaction check
---> Package epel-release.noarch 0:7-9 will be updated
---> Package epel-release.noarch 0:7-11 will be an update
--> Finished Dependency Resolution
Dependencies Resolved
================================================================================
Package Arch Version Repository Size
================================================================================
Updating:
epel-release noarch 7-11 epel 15 k
Transaction Summary
================================================================================ …