Friday, the 8th, I applied some updates and in the process PHP sessions stopped working. This broke all the web applications online.
I was not able to quickly determine what was wrong, so I restored the machine from an image made a couple of weeks prior.
I forgot that I had changed all of the web addresses and ftp addresses so when I reverted to the previously imaged machine, none of the addresses the web server was configured to listen to matched the domains it was hosting.
I had to manually edit all the addresses in the conf file. This took a little over two hours and as a result, service to all of the virtual domains was restored shortly after 1pm. The FTP service was restored by about 3pm.
I have re-applied the updates that failed to work properly the first time, this time successfully, and imaged the machine with the updated addresses so if another restore is necessary in the future it won’t require recreating the httpd configuration by hand.