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Note
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RDS (Relational Database Service)
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RDS is a managed SQL DB service
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Multi AZ setup for DR (Disaster Recovery)
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Have to set Maximum Storage Threshold
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Read Replicas: here
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Multi-AZ setup: here
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Amazon RDS Proxy: here
RDS
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It’s a managed DB service for DB that use SQL as a query language
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It allows you to create databases in the cloud that are managed by AWS
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Postgres
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MySQL
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MariaDB
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Oracle
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Microsoft SQL Server
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Aurora (AWS Proprietary database)
Advantage over using DB on EC2
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RDS is a managed service:
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Automated provisioning, OS patching
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Continuous backups and restore to specific timestamp
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Monitoring dashboards
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Read replicas for improved read performance
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Multi AZ setup for DR (Disaster Recovery)
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Maintenance windows for upgrades
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Scaling capability (vertical and horizontal)
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Storage backed by EBS (gp2 or io1)
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But you can’t SSH into your instances
RDS - Storage Auto Scaling
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Helps you increase storage on your RDS DB instance dynamically
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When RDS detects you are running out of free database storage, it scales automatically
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Avoid manually scaling your database storage
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You have to set Maximum Storage Threshold (Maximum limit for DB storage)
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Automatically modify storage if:
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Free storage is less than 10% of allocated storage
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Low-storage lasts at least 5 minutes
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6 hours have passed since last modification
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Useful for applications with unpredictable workloads
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Supports all RDS database engines
Read Replicas for read scalability
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Up to 5 Read Replicas
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Within AZ, Cross AZ or Cross Region
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Replication is ASYNC, so reads are eventually consistent
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Replicas can be promoted to their own DB
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Applications must update the connection string to leverage read replicas
Read Replicas - Use Cases
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You have a production DB that is taking on normal load
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You want to run a reporting application to run some analytics
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You create a Read Replica to run the new workload there
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Read replicas are used for SELECT (=read) only kind of statements (not INSERT, UPDATE, DELETE)
Network Cost
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In AWS there’s a network cost when data goes from one AZ to another
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For RDS Read Replicas within the same region, you don’t pay that fee
RDS Multi AZ (Disaster Recovery)
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SYNC replication
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One DNS name - automatic app failover to standby
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Increase availability
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Failover in case of loss of AZ, loss of network, instance or storage failure
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No manual intervention in apps
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Not used for scaling
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You can set Read Replicas as Multi AZ for disaster recovery
RDS - From Single-AZ to Multi-AZ
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Zero downtime operation (no need to stop the DB)
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Just click on “modify” for the database and enable “Multi AZ”
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The following happens internally
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A snapshot is taken
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A new DB is restored from the snapshot in a new AZ
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Synchronization is established between the two databases
Amazon RDS Proxy
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Fully managed database proxy for RDS
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Allows apps to pool and share DB connections established with the database
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Improving database efficiency by reducing the stress on database resources and minimize open connections
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Serverless, autoscaling, highly available (multi-AZ)
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Reduced RDS & Aurora failover time by up 66%
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Supports RDS and Aurora
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No code changes required for most apps
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Enforce IAM Authentication for DB, and securely store credentials in AWS Secrets Manager
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RDS Proxy is never publicly accessible (must be accessed from VPC)
