What files do i need to back up incase of disaster ?
and the ISPConfig mysql database.
This are the directories that are possibly affected by an update. If you want to do a full backup of your server, you should backup all mysql databases and also the directory /var/www (or any other directory that is the web root in ispconfig on your server).
I recommend that you wait a few days with your update as ISPConfig 2.2.10 will be released these days and it contains a patch against clamav compilation problems on some older linux distributions which may cause troble during update.