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  • AWS RDBMS offering
  • Option-1 : on EC2
    • Provision Ec2
    • install RDBMS and maintain it (os patching, security update, etc)
  • Option-2 : AWS Aurora
  • Option-3 : AWS RDS

RDS

Intro

  • not serverless
  • regional
  • RDBMS | OLTP
  • migrate to Aurora 👈
  • involves significant systems administration effort
  • 2 options: custom + fully manages

RDS :: custom :yellow_circle:

  • RDS does not allow you to access the host OS of the database
  • use RDS custom
  • allow some customization capabilities of underlying DB and OS (limited) 🎯
  • only for SQL server and oracle DB.
  • First disable automation mode, take snapshot, then access it.

RDS :: fully managed :green_circle:

  • Automates below administrative tasks :

1. hardware provisioning

  • choose EBS volume type:
  • gp2
  • io1
  • choose RDS ec2 instance s :
  • compute family size
  • no access/ssh

2. database setup

  • choose Supported engine:
  • Postgres, MySQL, MariaDB, Oracle, Microsoft SQL Server, IBM DB2
  • Aurora (AWS Proprietary database, not open source)

3. High Availability

  • choose availability
  • setup single-AZ (default)
  • setup mutli-AZ
    • fault tolerance
    • SYNC replication b/w instance in diff AZ. 🎯
  • fact: Multi-AZ keeps the same connection endpoint url for all instance in AZ 👈
  • easily switch from Single-AZ to multi-AZ 👈

4. patching

  • Auto OS patching :: in maintenance window. 

    - Scenario : in Mutli-AZ setup :dart:
  - a. primary and standby, both will upgrade at same time with downtime ? ****
  - b. first primary, then standby. no downtime ?
  - c. first standby, then primary. no downtime ?

  • Running a DB instance as a Multi-AZ deployment can further reduce the impact of a maintenance 👈 

    - Perform maintenance on the standby.
- Promote the standby to primary.
- Perform maintenance on the old primary, which becomes the new standby.

5. Scalability

instance::scale (vertical)

  • Scaling involves resizing instances
  • which may require downtime.

instance::scale (horizontal) - read replica

  • Not built-in scaling
  • but can manually create - ASG and CW:alarm on these metric:
    • connection count
    • cpu utilization
    • READ/WRITE traffic
    • ...

  • or, manually create read replication anytime.

  • READ replica

  • each Read Replicas add new endpoints URL, with their own DNS name 👈
    • use case:
    • analytics application
    • can run Analytics
  • each Read Replica is associated with a priority tier (0-15). 🎯 🎯
    • In the event of a failover, Amazon Aurora will promote the Read Replica that has the highest priority.
    • If two or more Aurora Replicas share the same priority, then Amazon RDS promotes the replica that is largest in size
    • eg: tier-1 (16 terabytes), tier-1 (32 terabytes), tier-10 (16 terabytes), tier-15 (16 terabytes), tier-15 (32 terabytes)
  • Also, can promote as primary in DR, if stand-by not provisioned.

Underlying Storage

  • define:
  • threshold ( maz-size in GB )
  • trigger eg: free space < 10%, space runs last 5min, etc.
  • good for unpredictable workloads

6. DR support

option-1: PITR

  • Point in Time Restore
  • Continuous backups happens and goes to s3
  • can retore these backup to new database instance.

option-2: Stand-by replica

  • manually enable Multi AZ-setup for DR.
  • master-writer-DB (az-1) --> SYNC replica/free --> Stand-by-DB (az-2)
  • Automatic fail-over from master to standby in DR situation. :dart
  • R53 CNAME record will be updated to point to the standby database. 🎯 
      - R53 failover-record for RDS url1. 
    - url1 -x-> primary/active
    - url1 --active--> secondary/passive

option-3: Promote Read replica

  • cross-region-read replicas, is also possible : paid
  • promote any READ replica as main DB later based on priority and size

7. Security

Encryption

  • At-rest encryption:
  • Database master & replicas encryption using AWS KMS
  • If the master is not encrypted, the read replicas cannot be encrypted
  • To encrypt an un-encrypted database, go through a DB snapshot & restore as encrypted
  • can only enable encryption for an Amazon RDS DB instance when you create it, not after the DB instance is created 🎯
  • In-flight encryption:
  • TLS-ready by default, use the AWS TLS root certificates client-side.
  • use the same domain-name-1 for both the certificate and the CNAME record in Route 53.
  • Export cert in ACM
  • when create/modify RDS instance, configure it use custom cname domain-name-1.
  • RDS support TDE (transparent Data encryption) with Oracle and SQL 🎯
  • integrated with CloudHSM (store keys in single tenant hardware module.) 10_HSM_DVA.md
  • key managed by AWS
  • automatic Encryption/decry..

IAM Authentication 🎯

  • works with MySQL and PostgreSQL 👈
  • token has a lifetime of 15 minutes
  • can use IAM roles to ec2-i, to connect to your database (instead of username/pw). eg:
    • ecs (role-1) --> rds
    • lambda (role-1) --> rds
  • or, create one time password/token after cluster creation

Security Groups

  • Control Network access to your RDS / Aurora DB

8 DB backup

  • for automatic bkp , retention 1 to 35
  • for manual, retention - as long we want for maul backup.
  • on-prem MySQL/postgres DB --> create db-dumps( Percona XtraBackup) --> place in S3 --> then restore.
  • with automated backups, I/O activity is no longer suspended, since backups are taken from the standby 🎯

9 cloning

  • faster than backup > restore
  • uses copy-on-write - use same volume + for new changes additional storage allocated and data copied to it.
  • use case: create test env from prod instance.

4. more

4.1 RDS proxy

  • pools open connections.
  • reduces fail-over time by 66%
  • access privatey only
  • client --> RDS proxy --> RDs instance
  • img.png

4.2 performance

  • Uses SSD-based storage.
  • write instance DB + Read replica/s for improved read performance.
  • Up to 15 READ replica/s
  • within AZ, or
  • cross-AZ, or
  • cross-region (paid replication)
  • main-DB --> A-SYNC replication (free within region) --> Read Replicas

4.3 RDS::pricing

  • Charged based on instance class and storage used.
  • standby instance
  • read replica
  • inbound data transfer is free.
  • Outbound data transfer is charged based on the volume of data transferred outside of AWS

  • replication charge: cross-region only 🎯

  • Cost Optimization Tips

  • Use Reserved Instances: Commit to a 1 or 3-year term for discounts
  • Enable Auto-Scaling.
  • Choose the Right Storage.
  • take snapshot and delete db if you dont need. later on restore from snapshot. this will save money.

4.4 Integration with AWS Ecosystem

  • IAM, Lambda, CloudWatch, and Elastic Beanstalk.
  • Simplifies building serverless or event-driven architectures

5. demo

- create single DB RDB in region-1
- choose underlying ec2 type (memory optimzed), EBS volume
- DB admin + password + DB name
- backup/screenshot : 
  - enable + retention policy upto 35 days
  - backup window preferrence.
- enable STORAGE autoscaling, give maz size : 100 GB
- Connectivity : 
  - option-1: add "specified ec2-i", will automatically configure things (good for beginner)
  - option-2: Dont connect to Ec2-i
    - define VPC, subnet
    - allow public access
    - choose SG
    - port 
- Authentication : DB password or IAM
- Monitoring : Enable
- backup window pr
- Miantaincence window
- Enable deletion prevention 

 === READY to USE ===

- Check monitoring dashboard : CPU, Moemory, Connections, etc
- action:
  - create read replica
  - take Snapshot + migrate Snapshot + restore to point.
  - create read replica.

99. for DVA

img.png

100. exam

  • un-encrypted RDS, encrypt it:
  • take screenshot >> encrypted snapshot >> restore it as new DB : correct

  • take screesnhot >> encrypted while restoring ❌

  • PITR more

  • Takes an automatic daily snapshot (called a daily backup).
  • Continuously backs up transaction logs every 5 minutes to allow point-in-time recovery within the backup retention period.