Amazon Relational Database Service
|Initial release||October 26, 2009|
|Type||relational database SaaS|
Amazon Relational Database Service (or Amazon RDS) is a distributed relational database service by Amazon Web Services (AWS). It is a web service running "in the cloud" designed to simplify the setup, operation, and scaling of a relational database for use in applications. Complex administration processes like patching the database software, backing up databases and enabling point-in-time recovery are managed automatically. Scaling storage and compute resources can be performed by a single API call as AWS do not offer ssh connection to RDS instances.
Amazon RDS was first released on 22 October 2009, supporting MySQL databases.  This was followed by support for Oracle Database in June 2011,  Microsoft SQL Server in May 2012, PostgreSQL in November 2013, and MariaDB (a fork of MySQL) in October 2015,  and additional 80 features during 2017 .
In November 2014 AWS announced Amazon Aurora, a MySQL-compatible database offering enhanced high availability and performance, and in October 2017 a PostgreSQL-compatible database offering was launched.
New database instances can be launched from the AWS Management Console or using the Amazon RDS APIs. Amazon RDS offers different features to support different use cases. Some of the major features are:
Multi-Availability Zone (AZ) deployment
In May 2010 Amazon announce Multi-Availability Zone deployment support, Amazon RDS Multi-Availability Zone (AZ) allows to automatically provision and maintain a synchronous physical or logical “standby” replica, depending on database engine, in a different Availability Zone (independent infrastructure in a physically separate location). Multi-AZ database instance can be developed at creation time or modified to run as a Multi-AZ deployment later. Multi-AZ deployments aim to provide enhanced availability and data durability for MySQL, MariaDB, Oracle, PostgreSQL and SQL Server instances and are targeted for production environments. In the event of planned database maintenance or unplanned service disruption, Amazon RDS automatically fails over to the up-to-date standby, allowing database operations to resume without administrative intervention.
Multi-AZ RDS instances are optional and have a cost associated with them. When creating your RDS instance, the user is asked if they would like to use a Multi-AZ RDS instance.
Read Replicas allows different uses case such as to scale out for read-heavy database workloads. Available up to 5 replicas for MySQL, MariaDB, and PostgreSQL instances use the native, asynchronous replication functionality of their respective database engines,  have no backups configured by default and are accessible and can be used for read scaling. MySQL and MariaDB read replicas can be made writeable again since October 2012, PostgreSQL read replica do not support it. 
Performance metrics and monitoring
Performance metrics for Amazon RDS are available from the AWS Management Console or the Amazon CloudWatch API. In December 2015, Amazon announced an optional enhanced monitoring feature that provides an expanded set of metrics for the MySQL, MariaDB, and Aurora database engines.
Amazon RDS instances are priced very similarly to Amazon Elastic Compute Cloud (EC2). RDS is charged per hour and comes in two packages: On-Demand DB Instances and Reserved DB Instances. On-Demand instances are at an ongoing hourly usage rate. Reserved DB Instances require an up-front, one-time fee and in turn provide a discount on the hourly usage charge for that instance.
Apart from the hourly cost of running the RDS instance, users are charged for the amount of storage provisioned, data transfers and Input and Output operations performed. AWS have introduced Provisioned Input and Output Operations, in which the user can define how many IO per second is required by their application. IOPS can contribute significant cost to the total cost of running the RDS instance.
As part of the AWS Free Tier, the Amazon RDS Free Tier helps new AWS customers get started with a managed database service in the cloud for free. You can use the Amazon RDS Free Tier to develop new applications, test existing applications, or simply gain hands-on experience with Amazon RDS.
Database instance types
|Instance Type||Memory||EBS Optimized / Throughput||Cores||Network Performance|
|db.t2.micro||1 GB||N/A||1 cores||Low to Moderate|
|db.t2.small||2 GB||N/A||1 cores||Low to Moderate|
|db.t2.medium||4 GB||N/A||2 cores||Low to Moderate|
|db.t2.large||8 GB||N/A||2 cores||Moderate|
|db.t2.xlarge||16 GB||N/A||4 cores||Moderate|
|db.t2.2xlarge||32 GB||N/A||8 cores||High|
|db.r3.large||15.25 GB||N/A||2 cores||Moderate|
|db.r3.xlarge||30.5 GB||N/A||4 cores||Moderate|
|db.r3.2xlarge||61 GB||N/A||8 cores||High|
|db.r3.4xlarge||122 GB||N/A||16 cores||High|
|db.r3.8xlarge||244 GB||N/A||32 cores||10 Gigabit|
|db.r4.large||15.25 GB||437 Mbit/s||2 cores||Up to 10 Gbps|
|db.r4.xlarge||30.5 GB||875 Mbit/s||4 cores||Up to 10 Gbps|
|db.r4.2xlarge||61 GB||1750 Mbit/s||8 cores||Up to 10 Gbps|
|db.r4.4xlarge||122 GB||3500 Mbit/s||16 cores||Up to 10 Gbps|
|db.r4.8xlarge||244 GB||7000 Mbit/s||32 cores||10 Gbps|
|db.r4.16xlarge||488 GB||14000 Mbit/s||64 cores||25 Gbps|
|db.m4.large||8 GB||450 Mbit/s||2 cores||Moderate|
|db.m4.xlarge||16 GB||750 Mbit/s||4 cores||High|
|db.m4.2xlarge||32 GB||1000 Mbit/s||8 cores||High|
|db.m4.4xlarge||64 GB||2000 Mbit/s||16 cores||High|
|db.m4.10xlarge||160 GB||4000 Mbit/s||40 cores||10 Gigabit|
|db.m4.16xlarge||256 GB||10000 Mbit/s||64 cores||25 Gigabit|
|db.m3.medium||3.75 GB||N/A||1 cores||Moderate|
|db.m3.large||7.5 GB||N/A||2 cores||Moderate|
|db.m3.xlarge||15 GB||500 Mbit/s||4 cores||High|
|db.m3.2xlarge||30 GB||10000 Mbit/s||8 cores||High|
|Instance Type||Memory||EBS Optimized / Throughput||Cores||Network Performance|
|db.t1.micro||0.613 GB||N/A||1 cores||Very Low|
|db.m1.small||1.7 GB||N/A||1 cores||Low|
|db.m1.medium||3.75 GB||N/A||1 cores||Moderate|
|db.m1.large||7.5 GB||N/A||2 cores||Moderate|
|db.m1.xlarge||15 GB||N/A||4 cores||High|
|db.m2.xlarge||17.1 GB||N/A||2 cores||Moderate|
|db.m2.2xlarge||34.2 GB||N/A||4 cores||Moderate|
|db.m2.4xlarge||68.4 GB||N/A||8 cores||High|
|db.cr1.8xl||244 GB||N/A||32 cores||10 Gigabit|
Competitors and alternatives
Several other vendors provide cloud database services similar to Amazon RDS. Oracle offers Oracle Cloud, a database service supporting Oracle's database technology. Microsoft offers Windows Azure SQL, a service supporting the Microsoft SQL and other relational databases. Competitors supporting MySQL include RackSpace Cloud Databases , Google Cloud SQL, HP Cloud for MySQL, Xeround Cloud Database, and ClearDB.
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- Amazon RDS APIs
- Availability Zone
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