We have developed centralized Point of Sales(POS)-(codeigniter/MySQL) system for 8 shops. All files and database in online server and shops can access POS system online. management can see real time sales data online.
We had a problem, with our slow internet connection it is difficult to do system operations online. Then we are decided install separate systems locally for all 8 shop (because locally hosted systems runs very fast and no issue when network fails) , If local POS system fails then user can use online system. and replicate 8 shops sales data, stock data, etc into online server every 15mins.
what happen if internet connection drops while replication time, Is it automatically continue or replication fail? please suggest good replication tool supports both master-slave, slave-master replication methods.
please suggest a solution, we need 100% reliable solution because system will deal with money.