Amazon Web Services

https://chartio.com/resources/tutorials/understanding-amazon-auroras-multi-az-deployment/

- AWS Cloud는 여러 개의 regions으로 이루어짐 -> Oregon, North Virginia, Ireland, Tokyo

- 그리고 각 각의 region 안에 Availability zones라고 불리는 물리적 데이터 센터 여러 개가 존재

 Availability Zone?

- 많은 regions에 2-3 개의 다른 Availability Zone이 있음.  

- AWS 대시보드를 이용해 인스턴스를 만들 때, Availabilty Zone을 선택해야 함 ( 내가 or 시스템이 선택)

- regions는 특정 문자열로 라벨링 됨

 예 ) us-west-2 - Oregon, us-west-1- California

 

Storage Layers Vs Server Instances

- server instance : 데이터베이스 structure를 제어하고 storage layer안에 있는 데이터를 routing 하는 물리적 기기

- storagge later : 데이터베이스에 있는 모든 실제 데이터를 가상적으로 표현하는 SSD-backed  

                       어떠한 실제 위치나 기기에 있는 게 아닌 virtualized 된 것!!!

 

 

In nearly all cases using Amazon Web Services, it is standard practice for the storage layer (where all the data resides) to be redundantly stored across all the Availability Zones within the given Region at no extra cost. In the event that one Availability Zone goes offline for some reason (as unlikely as that might be), the system is already in place to instantly and automatically continue the services of your database through an identical copy of the storage layer from one of the other connected Availability Zones.

This is where Multi-AZ Deployment comes in for services like Amazon Aurora. Just like the automatic redundancy of the data in your storage layer, a Multi-AZ Deployment means that your server instance is also redundantly copied across multiple Availability Zones. For this reason, any Amazon Aurora Multi-AZ Deployment is assured that should a single Availability Zone go offline where the physical server instance machine resides, an automatic failover is initiated onto an up-to-date standby replication in another connected Availability Zone.