RDS+Aurora+Elasticache

Question 1

What is RDS?

Answer 1

RDS is a relational database service. It’s managed service for DBs that use SQl query language. It allows you to create databases in the AWS cloud. These include Postgress, Maria DB, MySQL Oracle, Microsoft SQL

Question 2

What are the advantages of using RDS?

Answer 2

RDS is a managed service that provides automated provisioning of databases and patching, continuous backups, and restores points in time. there are read replicas for improved read performance. Multi AZ setup for DR (Disaster Recovery)
• Maintenance windows for upgrades
• Scaling capability (vertical and horizontal)
• Storage backed by EBS (gp2 or io1)
• BUT you can’t SSH into your instance

Question 3

RDS Back-Ups?

Answer 3

RDS backups are automatically enabled, full daily backup, logs are backed up every 5 mins. can restore to point in time 5 mins ago. & day retention can be increased to 35 days.

Question 4

RDS auto-scaling?

Answer 4

Automatically scales storage if storage is running out. Requires setting a maximum threshold limit. if free storage reaches less than 10% or low storage lasts more than 5 mins and it has been 6 hours since the last modification then it will trigger an auto-scaling.

Question 5

Read Replicas?

Answer 5

Read replicas are ASYNC replication. up to 5 read replicas within, cross AZ or region. reads are eventually consistent.

Question 6

Read Replicas Network costs?

Answer 6

There is no network cost for read replicas with a single region, however, cross-region replication has cost associated with it.

Question 7

Read Replicas DR?

Answer 7

DR has SYNC replication in Multi-AZ. Multi-AZ replication is free and uses one DNS name for failover. if the DB fails there is an automatic failover to standby DB

Question 8

RDS Encryption and security?

Answer 8

At rest encryption is possible with AWS KMS AE 256, Encryption has to be defined at launch time. If Master is not encrypted then replicas won’t be encrypted.
In-flight encryption with SSL certificates with trust certificates.

Question 9

What is Aurora?

Answer 9

Propretiary service, compatible with Progres and MySQL. Cab ne from 10GB up to 128TB, up to 15 replicas where MySQl is 5 replicas.

Question 10

Aurora high availability

Answer 10

6 copies of your data across 3 AZ:
• 4 copies out of 6 needed for writes
• 3 copies out of 6 need for reads
• Self healing with peer-to-peer replication
• Storage is striped across 100s of volume

1 master 15 replicas self healing.

Question 11

Aurora write and read endpoint

Answer 11

These are points for client contact, write endpoint for writing, and read endpoint is for read replicas.

Question 12

Aurora Security?

Answer 12

Aurora Security
• Similar to RDS because uses the same engines
• Encryption at rest using KMS
• Automated backups, snapshots and replicas are also encrypted
• Encryption in flight using SSL (same process as MySQL or Postgres)
• Possibility to authenticate using IAM token (same method as RDS)
• You are responsible for protecting the instance with security groups
• You can’t SSH

Question 13

Aurora Serverless

Answer 13

Automated database 
instantiation and auto
- scaling based on actual 
usage
• Good for infrequent, 
intermittent or 
unpredictable workloads
• No capacity planning 
needed
• Pay per second, can be 
more cost
-effective

Question 14

What’s Aurora multi-master?

Answer 14

This is useful for failover, where every node has RW unlike normal where there is only one master.

Question 15

What is elasticache?

Answer 15

Elasticache does a similar service as RDS does for databases. It helps get managed Redis and Memcache.
These are in-memory databases, these remove the load of the databases for read-heavy loads. it reduces latency and provides high performance.

Question 16

Redis vs MemcacheD

Answer 16

Redis is all about the high availability of read replicas and provides backup and restore features whereas Memcache is all about cache with no back up and restore feature. it’s a multithread architecture and is about multi nodes for data sharding.

Question 17

Important ports

Answer 17

Important ports:

FTP: 21

SSH: 22

SFTP: 22 (same as SSH)

HTTP: 80

HTTPS: 443

Question 18

RDS Ports

Answer 18

RDS Databases ports:

PostgreSQL: 5432

MySQL: 3306

Oracle RDS: 1521

MSSQL Server: 1433

MariaDB: 3306 (same as MySQL)

Aurora: 5432 (if PostgreSQL compatible) or 3306 (if MySQL compatible)