Scale up Scale down vs Scale In Scale Out

 

Scale In /Out	Scale Up/Down
Downtime: No downtime when provisioning in cloud	Downtime to some extent as there will be migration of code and configuration. No downtime when scaling process happens however migration of code configuration kicks off post scaling results in downtime.
Scenario: When code is alright, however no of users during the peak increases and server is unable to serve request. Increase no of boxes or instance to distribute loads of users across . Load balancing of users or distribution of users to serve request.	Scenario : When bad code or design leads to more CPU and memory utilizations. Need to increase server capacity
No sticky session Out proc session	In Proc session or state server session will do.