We have around 14 eCommerce sites which are working in 2 LAMP server. Two sites in server one and second server consist of rest of the sites. There is one central DB in which we are syncing all the data from different site using CRON on every 10 minutes. This CRON and along with other CRON jobs which are used for syncing and its giving huge load and servers are going down due to this.
Diagram of current server architecture:
As we have different structure of central DB, I could not use replication. Or am I wrong on this. Which is the best method I can look into for syncing more live.