I'm reading about different strategies for load balancers and one of them is hashing by the source IP (or the session ID). As far as I understand the idea behind that is to connect every user with a specific server, which can allow storing data about a particular user on the matching server. The examples I found are game servers (in case of disconnection user will be connected to the same server) and e-commerce websites (to store items in the cart for not logged-in users).
However, this strategy looks off to me from the availability perspective. What happens if some nodes failover? Will all users from the matching IP addresses won't be able to use the service then?
- If not - how the fallback is implemented (maybe you can reference a nice article)?
- If yes - in what use cases it is justified to use such a strategy? At the first glance, it doesn't seem to me that using it for game servers and e-commerce is a good idea