backup

    • preferred backup window
    • backup retention period
    • I/O suspension for single
    • Point-In-Time Recovery

  • snapshot

    • DB Snapshots make entire DB instance
    • from one region to another region,a copy retain in that region
    • Because KMS encryption keys are specific to the region that they are created in, encrypted snapshot cannot be copied to another region

    • DB Snapshot Sharing

      • DB snapshot that uses an option group with permanent or persistent options cannot be shared
      • KMS key policy must first be updated by adding any accounts to share the snapshot with, before sharing an encrypted DB snapshot

  • replication

    • routing read queries from applications to the Read Replica
    • Failover mechanism automatically changes the DNS record of the DB instance to point to the standby DB instance

    • Multi-AZ deployment

      • read-only traffic, use a Read Replica.
      • synchronous standby replica in a different Availability Zone
      • must be in same region

      • Read Replica

        • RDS sets up a secure communications channel between the source DB instance and the Read Replica, if that Read Replica is in a different AWS region from the DB instance
        • replication link is broken, A Read Replica can be promoted to a new independent source DB
        • use some tools like HAPROXY, with two url ,one for write one tor read

  • security

    • Encryption enabled at creating, can not change key later
    • Once encryption, log,snapshot,autobackup, replica are encripted
    • Cross region replicas and snapshots copy does not work since the key is only available in a single region
    • Database security groups default to a “deny all” access mode

  • monitor

    • 监控的metric 16 项, ReplicaLag
    • Backup not notify for snapshot

  • maintenance

    • Multi-AZ deployment, preform standby, promote standby, preform old primary
    • RDS takes two DB snapshots , before upgrade, after upgrade

Relation Database Service – RDS Overview

  • 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 secondary instance that can be failovered to seamlessly when a problem occurs.
    • provides elasticity & scalability by enabling MySQL, MariaDB, or PostgreSQL Read Replicas to increase read scaling.
    • supports MySQL, MariaDB, PostgreSQL, Oracle, Microsoft SQL Server, and the new, MySQL-compatible Amazon Aurora DB engine
    • in addition to the security in the database package, IAM users and permissions can help 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.

RDS Components

  • DB Instance
    • 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 Amazon AWS command line tools, Amazon 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 Amazon 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 several 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 Groups
    • 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
  • DB Option Groups
    • Some DB engines offer tools that simplify managing the databases and making the best use of data.
    • Amazon 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 Interfaces

  • 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

RDS Pricing

  • Instance class
    • Pricing is based on the class (e.g., micro, small, large, xlarge) of the DB instance consumed.
  • Running time
    • 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
    • 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.
  • Backup storage
    • 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.
  • Data transfer
    • Internet data transfer in and out of your DB instance.
  • Reserved Instance
    • In addition to regular RDS pricing, reserved DB instances can be purchased

Further Reading

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