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Amazon Relational Database Service (Amazon RDS)

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  5. Amazon Relational Database Service (Amazon RDS)
  • service to simplify the setup, operations, and scaling of a relational database on AWS.
  • Thus, spend more time focusing on application and schema
  • RDS offload common tasks as
    • backups
    • patching
    • scaling
    • replication
  • streamline installation of database software and provisioning of infrastructure capacity.
  • can launch many popular SQL database engines
  • simplifies maintenance by automating common administrative tasks on a recurring basis
  • easily replicate data to increase availability, improve durability
  • exposes database endpoint to which client software can connect and execute SQL.
  • does not provide shell access to Database (DB) Instances,
  • restricts access to certain system procedures and tables requiring advanced privileges.
  • use same tools to query, analyze, modify, and administer the database.

Database (DB) Instances

  • is an isolated database environment deployed in private network segments in the cloud.
  • RDS provides API to create and manage one or more DB Instances.
  • each DB Instance runs and manages a popular commercial or open source database engine
  • RDS supports the database engines as
    • MySQL
    • PostgreSQL
    • MariaDB
    • Oracle
    • SQL Server
    • Amazon Aurora
  • launch a new DB Instance by
    • calling the CreateDBInstance API
    • by using the AWS Management Console.
  • existing DB Instances can be altered or resized using the ModifyDBInstance API.
  • Database Instance can contain multiple different databases
  • create and manage within DB Instance by executing SQL commands with RDS endpoint
  • existing databases can be migrated to RDS

RDS Benefits

  • RDS increases database operational reliability by applying consistent deployment and operational model.
  • High consistency level is achieved by limiting types of changes that can be made to RDS.
  • It simplify common tasks in operating a relational database.

RDS Database Engines

MySQL:

  • most popular open source databases.
  • RDS for MySQL supports MySQL 5.7, 5.6, 5.5 and 5.1.
  • engine runs open source Community Edition with InnoDB as the default and recommended database storage engine.
  • Amazon RDS for MySQL can connect using MySQL Workbench or SQL Workbench/J.
  • Amazon RDS for MySQL supports Multi-AZ deployments for high availability and read replicas for horizontal scaling.

PostgreSQL

  • most widely used open source database engine
  • Has rich set of features and advanced functionality.
  • RDS supports DB Instances supports several versions and multiple releases of PostgreSQL – 9.5.x, 9.4.x, and 9.3.x.
  • RDS PostgreSQL uses tools like pgAdmin and JDBC/ODBC drivers.
  • RDS PostgreSQL also supports Multi-AZ deployment for high availability and read replicas for horizontal scaling.

MariaDB

  • It is another popular open source database engine
  • built by the creators of MySQL
  • It has enterprise tools and functionality.
  • AWS supports MariaDB version 10.0.17
  • RDS fully supports the XtraDB storage engine for MariaDB DB Instances
  • RDS also support for Multi-AZ deployment and read replicas.

Oracle

  • popular commercial relational databases
  • used in enterprise
  • RDS supports Oracle 11g and Oracle 12c.
  • RDS supports access to schemas on a DB Instance using Oracle SQL Plus.

Microsoft SQL Server

  • popular commercial relational database
  • used in enterprise
  • DBAs in RDS can connect to their SQL Server DB Instance in the cloud
  • Supports native tools like SQL Server Management Studio.
  • RDS support SQL Server 2008 R2, SQL Server 2012, and SQL Server 2014.

Licensing

  • RDS Oracle and Microsoft SQL Server are commercial software products
  • Need appropriate licenses to operate in cloud.
  • AWS provides two licensing models
    • License Included – license held by AWS and included in the Amazon RDS instance price.  For Oracle, only Standard Edition One provided
  • Bring Your Own License (BYOL) – User has to provide license. For Oracle appropriate Oracle Database license for DB Instance class and Oracle Database edition is needed.

Amazon Aurora

  • It offers enterprise-grade commercial database technology
  • offers simplicity and cost effectiveness of an open source database.
  • It is fully managed service,
  • It is MySQLcompatible out of the box
  • It can deliver up to five times the performance of MySQL without requiring changes
  • Aurora DB cluster consists of two different types of instances as
    • Primary Instance – main instance, supporting read and write workloads. Each Amazon Aurora DB cluster has one primary instance.
    • Aurora – Replica
      • secondary instance supporting only read operations. Each DB cluster can have up to 15 Amazon Aurora Replicas.
      • multiple Aurora Replicas, can distribute the read workload among various instances, increasing performance.
      • Can also locate Aurora Replicas in multiple Availability Zones to increase database availability.

RDS Storage Options

  • RDS is developed using Amazon EBS
  • Hence, can select storage option based on performance and cost requirements.
  • Based on database engine and workload, can scale up to 4 to 6TB in provisioned storage and up to 30,000 IOPS.
  • RDS supports three storage types namely – Magnetic, General Purpose (Solid State Drive [SSD]), and Provisioned IOPS (SSD).
  • Magnetic Storage:
    • Also called standard storage.
    • offers cost-effective storage for applications with light I/O requirements.
  • General Purpose (SSD):
    • also called as gp2.
    • provide faster access than magnetic storage.
    • can provide burst performance to meet spikes
    • ideal for small- to medium-sized databases.
  • Provisioned IOPS (SSD):
    • designed for I/O-intensive workloads, sensitive to storage performance and consistency in random access I/O throughput.

RDS Backup

  • RDS offers a consistent operational model for backup and recovery for all database engines
  • RDS offers two mechanisms for database backup – Automated backups and Manual snapshots.
  • Critical metric for backup, are
    • RPO – maximum period of data loss, acceptable in failure or incident.
    • RTO – maximum amount of downtime, permitted to recover from backup and resume processing.
  • Automated Backups
    • continuously tracks changes and backs up database.
    • RDS creates a storage volume snapshot of DB Instance, backing up entire DB Instance and not individual databases.
    • It can occur daily during a configurable 30-minute maintenance window called the backup window.
    • backups are kept for a configurable number of days, called backup retention period.
    • Can restore DB Instance to any specific time during this retention period, creating a new DB Instance.
  • Manual DB Snapshots
    • Can perform manual DB snapshots at any time.
    • Database snapshot can be initiated and created as frequently as required.
    • Then restore DB Instance to specific state in DB snapshot at any time.
    • Database snapshots can also be created with RDS console or the CreateDBSnapshot action.

RDS Recovery

  • RDS permits to recover database quickly with automated or manual DB snapshots.
  • cannot restore
    • from a DB snapshot to an existing DB Instance
    • when a new DB Instance is created when restored.
  • During DB Instance restore , only default DB parameter and security groups are associated with restored instance.
  • After restore, associate any custom DB parameter or security groups used by instance from which restored.
  • In automated backups, RDS combines daily backups performed during predefined maintenance window with transaction logs

High Availability with Multi-AZ

  • It allows to create a database cluster across multiple Availability Zones.
  • Used for RDBMS to run in highly available and fault-tolerant manner
  • It reduce DB administrative task complexity
  • It increase availability of database using replication.
  • Can meet demanding RPO and RTO targets by using synchronous replication.
  • Can place secondary copy of database in another AZ for disaster recovery.
  • Its deployments are available for all RDS database engines.
  • We can have primary instance in a AZ and secondary instance in another AZ
  • Automatically replicate data from primary instance to secondary instance by synchronous replication.
  • Every AZ runs on its own physically distinct, independent infrastructure
  • Failover in event of
    • Loss of availability in primary Availability Zone
    • Loss of network connectivity to primary database
    • Compute unit failure on primary database
    • Storage failure on primary database

Scaling Up and Out

  • scaling up (or vertically scaling) is by getting a larger machine permits to process more reads and writes.
  • Scaling out (or horizontally scaling) is adding more machines
  • RDS can scale compute and storage vertically and DB engines scale horizontally.
  • Vertical Scalability or Scaling Up
    • adding additional compute, memory, or storage resources to database
    • to process more transactions, run more queries, and store more data.
    • RDS makes it simple and can be scheduled to occur during next maintenance window
    • to scale immediately use ModifyDBInstance action.
    • to change amount of compute and memory, select a different DB Instance class of database.
  • Horizontal Scalability with Sharding or Scaling Out
    • RDBMS can scale vertically before reaching maximum instance size.
    • Partitioning a large RDBMS into multiple instances or shards can handle more requests beyond capabilities of a single instance.
    • Partitioning, or sharding, allows to scale horizontally to handle more users and requests but requires additional logic in application layer.
  • Horizontal Scalability with Read Replicas or Scaling Out
    • read replicas offload read transactions from primary database and increase overall number of transactions.
    • RDS supports read replicas to scale out elastically
    • some common scenarios
      • Scale beyond capacity of a single DB Instance for read-heavy workloads.
      • Handle read traffic while source DB Instance is unavailable.
      • Offload reporting or data warehousing scenarios against a replica instead of primary DB Instance.

RDS Security

  • securing RDS DB Instances needs a comprehensive plan
  • Secure all layers commonly in database-driven systems – infrastructure resources, database, and network.
  • Use IAM policies to limit which actions AWS administrators can perform.
  • Deploy RDS DB Instances into a private subnet within Amazon VPC limiting network access to DB instance
  • Restrict network access by ACLs and security groups and limit inbound traffic to source IP addresses.
  • Create users and grant permissions to read and write to databases.
  • Control DB access by database engine specific access control and user management mechanisms.
  • protect confidentiality of data in transit and at rest with multiple encryption capabilities
  • Security features differ slightly from one engine to another
  • Use SSL to protect data in transit.
  • Encryption at rest is possible for all engines using KMS or Transparent Data Encryption
  • all logs, backups, and snapshots are encrypted for an encrypted RDS instance.
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