I've got an application using redis for cache, it works well so far. However we need spread our applications to different regions(thru dynamic DNS dispatcher via user locations, local user could visit nearest server). Considering the network limitation and bandwith, it's not likely to build a centralised redis. So we have to assign different redis for different regions. So the problem here is how can we handle the roaming case. User opens the app in location 1, while continuing using the app in location 2 without missing the cache in location1.