database 101

Question 1

Dynamo DB

Answer 1

fast and flexible NoSQL database service for all application that need consistent.

• Stored on DDS storage
• Spread across 3 geographically distinct data centers
• Eventual consistent reads
• Strong consistent read

Question 2

Eventual Consistent Reads

Answer 2

consistence across all copies of data is usually reached within a second. Repeating a read after a short time should return updated data (best READ performance)

Question 3

Strongly Consistent Reads

Answer 3

A strong consistent read returns a resutls that reflects all writes that received a successful response prior to the read

Question 4

Dynamo DB pricing

Answer 4

write throughput $0.0065 per hours for every 10 units

wread throughput $0.0065 per hours for every 50 units

storage is 25 cents per gig per per months

Good for reads!!!

Question 5

Redshift

Answer 5

fast powerful, fully manages, petabyte-scale data warehouse service in the cloud. Data warehouse.

Question 6

Redshift configuration

Answer 6

single node (160Gb)

multi-Node

• leader Node (manages client connection and receives queries)
• Compute note (store and perfom queires and computation) up to 128 compute nodes.

Question 7

Redshift - Columnar Data Storage

Answer 7

only columns are only involved in the queries are processed and columnar

Question 8

Redshift- advance compression

Answer 8

massive parallel processing or MPP pace so misson red redshift automatically distributes

data and query load across all nodes and ASM redshift makes it easy to add nodes to your data warehouse

and enables you to maintain phos query performance as your data warehouse grows.

Question 9

Redshif Priced

Answer 9

The first is compute node hours so this is the total number of hours you run across all your computer

nodes for the billing period.
one unit per node per hour.

So 300 data warehouse clustering running persistently for an entire month would incur 2160 instance
.

Question 10

Elasticashe

Answer 10

its a web service that makes it east to delopy, operate and scale an in-memory in the cloud.
used to improve latency and compute intensive.

Question 11

two different Elasticache

Answer 11

1. Memcached

2. Redis

Question 12

Memcached

Answer 12

memory object caching system.

Question 13

Redis

Answer 13

open-source in memory key-value store that supports data structures such as sorted sets and lists.

Question 14

EXAM TIPS** ElasticCache Exam Tips

Answer 14

ElastiCache supports Master/Slave replication and Multi-AZ which can be used to achieve cross AZ redundancy

typically you will be given a scenario where a particular database is under a lot of stress/load. you may be asked which service you should use to alleviate this.

ElasticCache is a good choice if your database is particularly read heavy and not prone to frequent changing.

Redshits is a good answer if the reason your database is feeling stress is because management keep running (online transaction analytics)OLAP transaction on it etc.

Question 15

Aurora

Answer 15

Amazon Aurora is a MySQL-compatible relational database engine that combines the speed of availability of high-end commercial database with a the simplicity and cost effectiveness of open source database. it is 5 times better performance than MySQL at a price point one tenth that of a commercial database.

Question 16

Aurora Scaling

Answer 16

starts with 10 GB scales in 10 GB increments to 64T

compute resources can scale up to 32vCPU an 244GB of memory

maintains 2 copies of your data in contained in each AZ with minimum of 3 AZ. 6 copies of your data.

Aurora is designed to transparently handle the loss of up to two copies of data without affecting database write availability and up to three copies without affecting read availability.

storage is self-healing.

only available in certain regions.

Question 17

Aurora Replicas

Answer 17

2 types of Replicas are available

Aurora Replicas (currently 15)

MySQL Read Replicas (currently 5)

Tier 0 is right than T1 and so on

Question 18

AWS Database Types Summary

Answer 18

RDS_OLTP - used for online transaction 
  -sql
  -mysql
  -PostgresSQL
  -Oracle
  -Aurora
  -MariaDB
DynamoDB - No Sql
Reshift - OLAP (warehousing)
Elasticache:
  -memcached
  -Redis

Question 19

RDS Mulit AZ?

Answer 19

uses DNS endpoint when create ADS once you turn on multi AZ

failover- you can reboot to test failover

Question 20

Read Replica

Answer 20

up to 5 read replicas

Question 21

Aurora Scaling

Answer 21

2 copies of your data is contained in each availability zone with minimum of 3 availability zones. 6 copies.

aurora is designed to transparently loss of 2 copies without affecting read and 3 without affecting write.

2 types of replica
Aurora Replica (15 replicas) and mysql read replica of aurora database up to 5.

Question 22

DynamoDB vs RDS

Answer 22

DynamoDB offers “push button” scaling. meaning that you can scale your database on the fly, without any downtime.

RDS is not so easy and you usually have to use a bigger instance size of to add a read replica

Question 23

DynamoDB

Answer 23

stored on ssd storage

spread across 3 geograpgically distinc data center

eventual consistent read (defauly around second)

consistenet read (under second)

Question 24

Redshift configuration

Answer 24

single Node (160GB)

multi-node

• leader node (manages client connection and receives queries)
• compute nodes(stored and perform queires and computations). up to 128 compute nodes.

Question 25

Elasticache

Answer 25

webservice that makes it easy to deploy,operate , and cale an in memory cache in the cloud. the service improves the preformance of web application by allowing you to retrieve information from fast, managed, in-memory caches, instead of relying entirely on slower disk-based databases. ElasticCache supports two open-source in-memomy caching engines : - memcached - redis **study FAQ RDS***

Question 26

VPS Overview

Answer 26

**know it well** virtual data center in the cloud amazon virtual private cloud (amazon VPC) lets you provision a logically isolated section of the amazon web service cloud where you can launch aws resources in a virtual network that you define. you have complete control over your virtual networking environment, including selection of your own IP address range, creation of subnets, and configuration of route tables and network gateways. you can easily customize the network configuration for your amazon virtual cloud. for example , you can create public-facing subnet for your webservers that has access to the internet, and place your backend systems such as databases or application servers in a private-facing subnet with no internet access. you can leverage multiple layers of security, including security groups and network access control lists, to help control access to Amazon EC2 instances in each subnet. additionally can create a Hardware Virtual Private Network(VPN) connection between your corporate datacenter and your VPC and leverage the AWS cloud as an extension of your corporate datacenter.

Question 27

what can you do in a VPC?

Answer 27

Launch instances into a subnet of your choosing assign custom IP address ranges in each subnet Configure route tables between subnets create internet gateway and attach in to our vpc ( one internet gateway to a vpc) much better security control over your AWS resources(use subnet to block specific IP addresses or netword acl to block Ip addresses instance secruity group(across AZ and mutliple subnets) subnet network access contol lists (ACLS) - block IP addresses

Question 28

default VPC vs Custom VPC

Answer 28

Default vpc is user friendly, allowing you to immediately deploy instances. all subnets in default VC havea route out to the internet (dont get private subnet in VPC) each EC2 instance has both a public and private IP address (if custome we wont get both unless we set them up)

Question 29

VPC Peering

Answer 29

allows you to connect one VPC with another via direct network route using private IP addresses instances behave as if they were on the same private network you can peer VPC's with other AWS accounts as well as with other VPCs in the same account peering is in a star configuration ie 1 central VPC peers with 4 other NO TRANSATIVE PEERING

Question 30

EXAM tips for VPC

Answer 30

Think of a VPC as logical datacenter in AWS consist of IGWs (or virtual private gateway), Route Tables, Netweork access control list (NACL), subnets, and security groups 1 subnet - 1 AZ Security Groups are Stateful, Network access control lists are stateless NO TRANSITIVE PEERING