In Web applications, users session can store a lot of data:
- Information about the users profile
- User roles
- Temporary data (for example, wizard step data)
However, such storage can be a real headache if we have few backend servers that serve this application. To provide load-balancing and fault-tolerance in the service, session data should be stored in external storage (redis, memcached, sql). Appearance of new storage adds stress to supporting and performance.