Natural Order Development

Today, I was attempting to upgrade my installed packages using yum on Centos Linux. Except that yum spun off into 404 land. The command looked like this:

$ sudo yum -y upgrade
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
 * addons: centos.mirror.netriplex.com
 * base: mira.sunsite.utk.edu
 * extras: repo.genomics.upenn.edu
 * updates: centos.aol.com
http://centos.mirror.netriplex.com/5.5/addons/i386/repodata/repomd.xml:
[Errno 14] HTTP Error 404: Not Found
Trying other mirror.
http://dist1.800hosting.com/centos/5.5/addons/i386/repodata/repomd.xml:
[Errno 14] HTTP Error 404: Not Found
Trying other mirror.
http://mirror.cisp.com/CentOS/5.5/addons/i386/repodata/repomd.xml:
[Errno 14] HTTP Error 404: Not Found
Trying other mirror.
http://mirror.fdcservers.net/centos/5.5/addons/i386/repodata/repomd.xml:
[Errno 14] HTTP Error 404: Not Found
Trying other mirror.
http://mirror.its.uidaho.edu/pub/centos/5.5/addons/i386/repodata/repomd....
[Errno 14] HTTP Error 404: Not Found
Trying other mirror.
[...]

Basically yum ran through every single mirror and got nothing but 404 errors. I thought something might have gotten broken with yum or maybe the entire Internet changed overnight to a new repository layout (not likely but it has happened before). Well a simple Google for yum 404 led to some message threads that basically said yum's caches were out of data. The solution was so simple I frankly had a hard time believing that all I had to do was issue the command:

yum clean all

One command, caches cleaned and off yum went to do the upgrade I wanted.

Very simple, very happy, thanks Google!