Amazon Relational Database Service (RDS) is a web service that makes it easier to set up, operate, and scale a relational database in the cloud.
RDS provides cost-efficient, resizable capacity for an industry-standard relational database and manages common database administration tasks.
RDS features & benefits
CPU, memory, storage, and IOPs can be scaled independently.
manages backups, software patching, automatic failure detection, and recovery.
automated backups can be performed as needed, or manual backups can be triggered as well. Backups can be used to restore a database, and the RDS restore process works reliably and efficiently.
provides high availability with a primary instance and a synchronous standby secondary instance that can be failovered to seamlessly when a problem occurs.
provides elasticity & scalability by enabling Read Replicas to increase read scaling.
supports MySQL, MariaDB, PostgreSQL, Oracle, Microsoft SQL Server, and the new, MySQL-compatible Amazon Aurora DB engine
supports IAM users and permissions to control who has access to the RDS database service
databases can be further protected by putting them in a VPC, using SSL for data in transit and encryption for data in rest
However, as it is a managed service, shell (root ssh) access to DB instances is not provided, and this restricts access to certain system procedures and tables that require advanced privileges.
is a basic building block of RDS
is an isolated database environment in the cloud
each DB instance runs a DB engine. AWS currently supports MySQL, MariaDB, PostgreSQL, Oracle, and Microsoft SQL Server & Aurora DB engines
can be accessed from AWS command line tools, RDS APIs, or the AWS Management RDS Console.
computation and memory capacity of an DB instance is determined by its DB instance class, which can be selected as per the needs
for each DB instance, 5 GB to 6 TB of associated storage capacity can be selected
storage comes in three types: Magnetic, General Purpose (SSD), and Provisioned IOPS (SSD), which differ in performance characteristics and price
each DB instance has a DB instance identifier, which is customer-supplied name and must be unique for that customer in an AWS region. It uniquely identifies the DB instance when interacting with the RDS API and AWS CLI commands.
each DB instance can host multiple databases, or a single Oracle database with multiple schemas.
can be hosted in an AWS VPC environment for better control
Regions and Availability Zones
AWS resources are housed in highly available data center facilities in different areas of world, these data centers are called regions which further contain multiple distinct locations called Availability Zones
Each AZ is engineered to be isolated from failures in other AZs, and to provide inexpensive, low-latency network connectivity to other AZs in the same region
DB instances can be hosted in different AZs, an option called a Multi-AZ deployment.
Amazon automatically provisions and maintains a synchronous standby replica of the DB instance in a different AZ.
Primary DB instance is synchronously replicated across AZs to the standby replica
Provides data redundancy, failover support, eliminate I/O freezes, and minimize latency spikes during system backups.
security group controls the access to a DB instance, by allowing access to the specified IP address ranges or EC2 instances
DB Parameter Groups
A DB parameter group contains engine configuration values that can be applied to one or more DB instances of the same instance type
help define configuration values specific to the selected DB Engine for e.g. max_connections, force_ssl, autocommit
supports default parameter group, which cannot be edited.
supports custom parameter group, to override values
supports static and dynamic parameter groups
changes to dynamic parameters are applied immediately (irrespective of apply immediately setting)
changes to static parameters are NOT applied immediately and require a manual reboot.
DB Option Groups
Some DB engines offer tools or optional features that simplify managing the databases and making the best use of data.
RDS makes such tools available through option groups for e.g. Oracle Application Express (APEX), SQL Server Transparent Data Encryption, and MySQL memcached support.
RDS can be interacted with multiple interfaces
AWS RDS Management console
Command Line Interface
Programmatic Interfaces which include SDKs, libraries in different languages, and RDS API
Pricing is based on the class (e.g., micro, small, large, xlarge) of the DB instance consumed.
Billed by the instance-hour, which is equivalent to a single instance running for an hour for e.g., a single instance running for two hours = two instances running for one hour, both consume 2 instance-hours.
if a DB instance runs for only part of an hour, full instance-hour is charged
Storage capacity provisioned for the DB instance is billed per GB per month
If the provisioned storage capacity is scaled within the month, the bill will be pro-rated.
I/O requests per month
Total number of storage I/O requests made in a billing cycle.
Automated backups & any active database snapshots consume storage
Increasing backup retention period or taking additional database snapshots increases the backup storage consumed by the database.
RDS provides backup storage up to 100% of the provisioned database storage at no additional charge for e.g., if you have 10 GB-months of provisioned database storage, RDS provides up to 10 GB-months of backup storage at no additional charge.
Most databases require less raw storage for a backup than for the primary dataset, so if multiple backups are not maintained, you will never pay for backup storage.
Backup storage is free only for active DB instances.
Internet data transfer in and out of your DB instance.
In addition to regular RDS pricing, reserved DB instances can be purchased