Lync 2013: Save your cumulative update installation files!

In a perfect world your servers would always be at the current cumulative update release.  In reality, that does not always happen for a variety of reasons.  When the CU is applied, the updates installed are removed and replaced by log files.  This means that if you need to apply the CU to a rebuilt server after recovery, the files in the original install directory are useless.  Older CU's are not available for download after they are superseded.  It's a good idea to store the CU's in a separate rebuild directory with your certificates and other files needed to rebuild a failed server.  You don't want to be forced into installing an untested CU on all your servers because you cannot bring one server up to your deployed version.