Data Stores

Question 1

Describe & give examples of PERSISTENT data stores

Answer 1

Data is durable, survives reboots and restarts
eg: Glacier, S3, RDS

Question 2

Describe & give examples of TRANSIENT data stores

Answer 2

Data is temporarily stored before being passed on
eg: SNS, SQS, MQ

Question 3

Describe & give examples of EPHEMERAL data stores

Answer 3

Data is lost when service stops
EG: Memcached/Elasticache, EC2 Instance Store

Question 4

Describe what IOPS & Throughput measure

Answer 4

IOPS: How fast data can be read and written to a device
Throughput: How fast data can be moved to a time

Question 5

What does ACID (consistency model) stand for

Answer 5

Atomic - Transactions are “all or nothing”
Consistent - Transactions must be valid
Isolated - Transactions can’t affect each other
Durable - Complete transactions must stick around

Question 6

What does BASE (consistency model) stand for

Answer 6

Basic Availability - Values available even if stale
Soft-state - Might not be instantly consistent across stores
Eventual Consistency - Will achieve consistency at some point

Question 7

What are the differences between the ACID and BASE consistency models

Answer 7

ACID is slower and doesn’t scale as easily, but data is more consistently reliable
BASE is faster and scales easier, but data isn’t as consistently reliable