We have multiple data centers and are now planning to make this application active/active. Which means user can be load balanced. User generally uploads a file and it should be accessible on both sites.
We expect it will take upto 1 hr to replicate files in worst case scenario and we are not able to come up with good solution since cookies wouldn't work for us. What we really need is someway of storing User and Site eg: User A visited site X. Based on that information we can then redirect user to correct site. After one hour this info will expire and generate new info. I am planning to use memcached on httpd apache server accross 2 data centers to keep cache in sync. I understand latency will be a factor but I am assuming we can also do async and it shouldn't be that slow since we are only talking about small set of data. Need help from experienced users if they have any good suggestions on how to do this.