We'll be launching a mobile app (iOS, Android) soon. App is native with a local SQLite database. App is supposed to do scheduled database sync with a live online MySQL database connected to a PHP based backend system hosted on a Hostgator dedicated machine.
App audience is expected to be 10,000+. Now, as worst case scenario, if all of these apps/clients start sync at once, I think it'll be a disaster. It'll be like 10,000 visitor accessing a site at once and there may be outage or even server may go down.
A single sync request doesn't take much. Data returned is a few KBs.
Regardless of mobile app, API, PHP and MySQL optimizations, what should we optimize on server to sustain this spike of load? The bandwidth? uplink? simultaneous HTTP connections? simultaneous database users? What you suggest what and how much for this scenario?