Amazon RDS

Relational Database Service

  • All relational DBs use Structured Query Language (SQL)
  • Best suited for OLTP (On Line Transaction Processing)
  • DBs are usually used in Enterprise applications/scenarios.
  • Amazon Relational Database Service is a distributed relational database service by AWS.
  • You can set up, operate, and scale a relational database in the AWS cloud.
  • It provides cost-efficient and resizable capacity
  • AWS will responsible to do hardware provisioning, database setup, patching and backups.
  • You only focus on your applications so you can give them the fast performance, high availability, security and compatibility they need.

Infrastructure Management

  • You are responsible for
    • Managing DB Settings
    • Building a relational DB schema
    • DB performance tuning
  • AWS is responsible for
    • Security and patching of the DB instances
    • Automated backups
    • Software updates for the DB engine
    • Multi-AZ with Synchronous replication between the active and standby DB instances
    • Automatic failover if Multi-AZ option
    • Providing the ability to create DB read replicas for DB read scaling

Supported Databases by AWS

  • Supported DBs
    • AWS Aurora
    • PostgreSQL
    • MariaDB
    • MySQL
    • MS SQL Server
    • ORACLE
  • Free Tier Details
    • 12 MONTHS FREE
    • 750 hours per month of db.t2.micro
    • 20 GB of general purpose (SSD) database storage
    • 20 GB of storage for database backups and database snapshots

RDS DB Instances

  • A DB instance is a virtual machine with database environment running in the cloud.
  • Can contain multiple user-created databases, accessed using the client tools and applications
  • DB instances created and modified with
    • AWS CLI
    • Amazon RDS API operations
    • AWS Management Console.
  • Each DB instance has a DB instance identifier and it must be unique for that customer in an AWS Region

DB instance classes and storage

  • The DB instance class determines the compute and memory capacity the instance
  • DB instance class types
    • Standard (balanced compute, memory, and networking)
      • Ex: db.m3, db.m4, db.m5
    • Memory Optimized (memory-intensive applications)
      • Ex: db.r3, db.r5, db.x1
    • Burstable Performance (burstable performance DB instance)
      • Db.t2, db.t3, db.t4g
  • Amazon RDS storage types
    • General Purpose SSD – offer cost-effective storage that is ideal for a broad range of workloads
    • Provisioned IOPS – designed to meet the needs of I/O-intensive workloads
    • Magnetic – low performance

RDS Backup

  • Two types of backup for your RDS DB instances
    • Automated backups
    • Manual backups

Automated backups

  • Amazon RDS creates and saves automated backups of your DB instance.
  • RDS creates a storage volume snapshot of your DB instance, backing up the entire DB instance.
  • Backups are stored in Amazon S3
  • The first snapshot is a full one, and then subsequent snapshots are incremental
  • Retention period: AWS RDS keeps the automated backup for 7 days by default
    • Min 0 days (means no retention)
    • Max 35 days
  • RDS automatically backs up the DB instances daily, by creating a storage volume snapshot of your DB instance including the DB transaction logs
    • You can choose the Backup Window time
    • Enabled by default, you can disable it by setting retention period to zero
  • Transaction logs are backed-up by RDS every 5 minutes
  • Automated backups are used for point-in-time DB instance recovery
  • It can restore the DB up to 5 minutes in time using the DB transaction logs and the automated snapshot
  • During your daily backup window, your I/O may be suspended (for standalone RDS deployments)
  • For Multi-AZ deployment, backups are taken from the standby DB instance
  • Automated backups are deleted when you delete your RDS DB instance

Manual backups

  • Manual snapshot not used for point-in-time recovery
  • These snapshots stored in Amazon S3
  • They are not deleted automatically when you delete your RDS instance. You have to manually delete from S3
  • It is recommended to take a final snapshot before deleting your RDS DB instance
  • Can be shared with other AWS accounts directly

Amazon RDS Multi-AZ Deployments – Disaster Recovery

  • Amazon RDS creates a primary DB Instance and synchronously replicates the data to a standby instance in a different Availability Zone
  • Amazon RDS detects and automatically recovers from the most common failure scenarios for Multi-AZ deployments.
  • Amazon RDS automatically performs a failover in the event of any of the following happens
    • Loss of availability in primary Availability Zone
    • Loss of network connectivity to primary
    • Compute unit failure on primary
    • Storage failure on primary

RDS Multi-AZ Deployments

  • You can select the Multi-AZ option during RDS DB instance launch or modify an existing standalone RDS instance
  • You can NOT read/write to the Standby RDS DB instance
  • You will be alerted by a DB instance event when a failover occurs. AWS RDS uses AWS SNS to send RDS events via SNS notifications
  • In Multi-AZ, snapshots and automated backups are done on Standby instance to avoid I/O suspension on Primary instance
  • Maintenance sequence of events in Multi-AZ:
    • Maintenance on Standby is performed
    • Standby promoted to Primary
    • Maintenance performed on old primary (Current Standby)

DB Read Replicas

  • RDS Read Scalability
  • A read replica is a replica of the primary RDS DB instance that can only be used for read operation
  • Asynchronous replication. Reads are eventually consistent
  • Read replicas are available in Amazon RDS for MySQL, MariaDB, PostgreSQL, Oracle, and SQL Server as well as Amazon Aurora
  • Within AZ, Cross AZ or Cross Region
  • Read replicas are used for SELECT
  • Shifting read intensive applications such as Business reporting, or Data Warehousing to read from read replicas as opposed to overload the primary DB

RDS Read Replicas – Use Cases

  • You have a production database that is taking on normal load
  • You want to run some analytics on your data
  • You create a Read Replica to run the new workload there
  • The production application performance is unaffected

Amazon Aurora

  • Aurora is a RDS from AWS (not open sourced)
  • Aurora database build on top of Postgres and MySQL
  • Aurora is AWS optimized and claims 5x performance improvement over MySQL and 3x over Postgres
  • Aurora storage automatically grows in increments of 10GB, up to 64 TB.
  • Aurora can have 15 replicas while MySQL has 5, and the replication process is faster
  • Aurora costs more than RDS (20% more) – but is more efficient

Amazon Aurora DB clusters

  • An Aurora cluster volume is a virtual database storage volume that spans multiple AZs, with each Az having a copy of the DB cluster data.
  • Primary DB instance
    • Supports read and write operations. Each Aurora DB cluster has one primary DB instance.
  • Aurora Replica
    • Can have up to 15 Aurora Replicas.
    • Maintain HA by locating Replicas in separate AZs.
    • Automatically fails over to an Aurora Replica in case the primary DB instance becomes unavailable.

Features of Aurora

  • Automatic fail-over
  • Backup and Recovery
  • Isolation and security
  • Industry compliance
  • Automated Patching with Zero Downtime
  • Advanced Monitoring
  • Routine Maintenance
  • Backtrack: restore data at any point of time without using backups
Amazon RDS

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