[AWS] RDS Multi-AZ + Read Replica

RDS, Aurora, Multi-AZ, Read Replica, RDS Proxy, RDS Aurora Serverless v2, Aurora Global Database

정의

RDS (Relational Database Service) = AWS 의 managed RDB. MySQL, PostgreSQL, MariaDB, Oracle, SQL Server, Aurora (AWS 자체).

Multi-AZ Deployment

flowchart LR
    Primary["Primary (AZ a)<br/>Master"]
    Primary -->|sync 복제| Standby["Standby (AZ b)<br/>passive"]
    Primary --> Client
    Note["Standby = 읽기 불가<br/>(HA 용)"]

• 동기 복제.
• AZ 장애 시 자동 failover (1-2분).
• Read 분산 불가 (Standby = passive).

Read Replica

flowchart LR
    Primary["Primary"]
    Primary -.async 복제.-> R1["Read Replica 1"]
    Primary -.async.-> R2["Read Replica 2"]
    Primary -.async (cross-region).-> R3["Read Replica 3<br/>(다른 region)"]
    Client -->|writes| Primary
    Client -->|reads| R1 & R2 & R3

• 비동기 복제 (lag 가능).
• 읽기 부하 분산.
• Cross-region 가능 (DR).
• Standalone DB 로 승격 가능.

Aurora vs RDS MySQL/PostgreSQL

	RDS MySQL/PG	Aurora MySQL/PG
스토리지	EBS	AWS 자체 분산 (3 AZ × 2 복제)
처리량	표준	3-5배 빠름
백업	snapshot	continuous 백업 (PITR)
Read Replica	5개 한도	15개 + reader endpoint
Failover	1-2분	< 30초
가격	약간 cheap	약간 비쌈
Serverless	옵션	Aurora Serverless v2

Aurora 분산 스토리지

flowchart TB
    Compute["Compute (DB engine)"]
    Compute --> Storage["Cluster Volume (자체)"]
    Storage --> AZa1["AZ a copy 1"]
    Storage --> AZa2["AZ a copy 2"]
    Storage --> AZb1["AZ b copy 1"]
    Storage --> AZb2["AZ b copy 2"]
    Storage --> AZc1["AZ c copy 1"]
    Storage --> AZc2["AZ c copy 2"]

• 6 copy, 3 AZ.
• quorum (4/6 write, 3/6 read).
• 2 copy 손실 OK (가용성), 3 copy 손실 OK (durability).

RDS Proxy

flowchart LR
    Lambda --> RDSProxy["RDS Proxy<br/>(connection pool)"]
    EC2 --> RDSProxy
    RDSProxy -->|pool 재사용| RDS[(RDS)]

• Connection pool 을 AWS managed 로.
• Lambda 의 connection 폭증 해결.
• failover 시간 단축.

Aurora Serverless v2

• 자동 scaling (0.5 ACU - 128 ACU).
• cold start 없음 (v1 의 결함 해결).
• 가변 워크로드 / dev / test.

Aurora Global Database

flowchart LR
    Primary["Primary Cluster (us-east-1)"]
    Primary -.<1s 복제.-> Sec1["Secondary (eu-west-1)"]
    Primary -.-> Sec2["Secondary (ap-northeast-1)"]
    Note["DR: < 1분 failover<br/>Read: 글로벌 분산"]

백업

종류	의미
Automated backup	매일 + WAL. PITR (Point-in-Time Recovery)
Manual snapshot	수동, 영구
Aurora Backtrack	옛 시점으로 DB 자체 회귀 (snapshot 없이)

흔한 함정

관련 위키

• postgresql, mysql-innodb
• connection-pool
• Redis Replication (비교)
• aws-vpc