AWS Solutions Architect Associate Certification preparation – short notes-IV

Into our fourth post in the AWS Solutions Architect Associate certification preparation series.

In our previous posts, we discussed the common topics including S3, EC2 etc… In this post, we will cover the databases section.

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[ Disclaimer : This is not a complete training material for the certification. This is just random (short) notes which we captured from course curricula, which will help the readers for their final revision/rewind before appearing for the exam. We do not offer any guarantee in passing the exam with this content ]
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Relational Databases

6 DBs available in AWS are – SQL server, Oracle, MySQL, PostgreSQL, Amazon Aurora, MariaDB

Multi-AZ for Disaster recovery and Read Replicas for Performance.
DynamoDB is amazon’s No SQL solution.
Redshift is the AMazon’s Datawarehousing solution (for Online Analytic processing -OLAP).
Elasticache – improves performance by in-memory cache in cloud. SUpports 2 open-source in-memory caching engines. – Memcached and redis

RDS runs on VMs but we cannot access those. AWS takes care of managing the VMs. RDS is NOT serverless (except Aurora)

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RDS Backups : Automated daily backups and snapshots. Retention period 1-35 days.
Automated backups are enabled by default. Data will be saved in S3, and you get space for free.
During backup window, IO will be suspended and there may be performance issue.

DB snapshots are manual.
Restored DB (from manual snapshot or Automated backup), will be a new RDS instance with new endpoint (URL)

[email protected] encryption is supported (with AWS KMS) for SQL server, Oracle, MySQL, PostgreSQL, Amazon Aurora, MariaDB. Stored data, backups and snapshots are all encrypted.
Multi-AZ : For disaster recovery. AWS will automatically switch to the secondary copy in case of any maintenance or disaster. supported for SQL server, Oracle, MySQL, PostgreSQL, and MariaDB. Amazon Aurora by it’s architecture supports multi-AZ failure.
Read-replica : are for performance improvment for read-intensive database instances. Read can be re-directed to any of the async copy of the actual instance. writes can be still done to the primary DB. Supported by MySQL, PostgreSQL, Amazon Aurora, MariaDB
Can have upto 5 copies/replicas of the primary. Can have read-replicas of read-replicas (performance may reduce).Automatic backups must be turned on.
We can have read-replicas that can have multi-AZ. Can create read-replicas of multi-az source DB.

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DynamoDB : AWS’s No SQL DB. Uses SSD and is spread across 3 separate geo areas.
Eventual consistant reads(default)- can ensure data consistency after 1-2 secs of write.
Strong consistant reads – Needed if data will be read by application within a second of write.
Redshift is used for Business intelligence. OLAP solution for Datawarehousing. available in 1 AZ at present(can’t span across multi)
Backup is by default with 1 day retention. Can be modified to max of 35days.
Always 3copies (1xOriginal+1xReplica+1xBackupinS3) kept.
For disaster recovery,Redshift can automatically replicate the snapshots to a S3bucket in different region.
Redshift configuration:
Single node with 160 GB or Multi-node (which will have a leader node – which receives the queries and manages client connections – and upto 128 compute nodes – which processes the queries and computations). Users will be charged for the hours the compute nodes are operating not the leader nodes.
[email protected] for Redshift using AES-256 encryption. Redshift takes care of KMS. We can manage Keys using HardwareSecurityModule(HSM) or AWS KMS.
Uses advanced level of compression, which identifies similar data and does compression.

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Amazon Aurora
MySQL compatible relational database engine, 5x better performance than MySQL.
start with 10G, increments by 10G upto 64TB. Compute resource can scale upto 32vCPUs and 244G memory.
6copies of data (2x copies in 3 AZs). Can loss 2 copies of data without affecting the write-ability. Can loss 3 copies without affecting the read-ability. Aurora read-replicas are better and can have upto 15 copies (5 for MySQL read-replicas). Automated failover (to read-replica) is supported.

Elasticache – improves performance by in-memory cache in cloud. SUpports 2 open-source in-memory caching engines. – Memcached (simple solution) and redis (Supports Multi-AZ and supports backups)

Another short post is coming to an end. Hope it was helpful and you enjoyed reading it. Please share your feedbacks as comments.

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