I ran into a problem where apache would not start due to some sort of mod_python error. This is typically something you only see on a busy server. If you get the following error:

[error] (28)No space left on device: mod_python: Failed to create global mutex 0 of 4 (/tmp/mpmtx175910).
Configuration Failed

Simply run the following to fix it:

echo "kernel.sem = 512 32000 100 512" >> /etc/sysctl.conf; sysctl -p; service httpd start