Hello,
I'm a professional PHP, MySQL developer with 4+ years experience. I can help you with this project.
My code designing approach will be like this,
1) Master website will have php page will save the database in a folder every 30 min.
2) Slave website will search and download the master websites backup database every 30 min.
3) Slave website's php codes will upload the database to its MySQL host every 30 min.
Please provide me more details about the project. Looking forward to hear from you.
Regards,
Ankur