Web Farm + XML file for data storage

We have a web farm with two web servers. We are using XML file (stored inside web application) for data storage and convert this XML file to Excel and then email the file once a new record is added to the XML file. We didn't realize that since we were on web farm we will be having two different XML files, one for each server. Moreover, these files will have different data. Any suggestions how we can handle this situation.?We have a web farm with two web servers. We are