Databases - Backups + Multi-AZ + Read Replicas

Question 1

Types of Backups

Answer 1

Automated Backups, Database Snapshots

Question 2

Automated Backups

Answer 2

allow you to recover your DB to any point in time within a retention period. they will take a full daily snapshot and will store transaction logs throughout the day

Question 3

Retention period range

Answer 3

1-35 days, 7 days by default

Question 4

Recover an automated backup

Answer 4

AWS will choose the most recent daily backup, and then apply transaction logs relevant to that day

Question 5

Which type of backup is enabled by default?

Answer 5

Automated

Question 6

Where is the backup data stored?

Answer 6

S3

Question 7

How much storage will you get?

Answer 7

Free storage space = size of your database

Question 8

When are backups taken?

Answer 8

within a defined window

Question 9

What will happen to storage I/O during the backup window?

Answer 9

may be suspended

Question 10

Are DB snapshots manual or automated?

Answer 10

Manual

Question 11

When the RDS instance is deleted, what happens to automated backups?

Answer 11

They are deleted.

Question 12

When the RDS instance is deleted, what happens to DB snapshots?

Answer 12

They are stored

Question 13

When the RDS instance is deleted, do you have a chance to make one final snapshot?

Answer 13

Yes.

Question 14

What happens when you restore either an automated backup or a DB snapshot?

Answer 14

the restored version of the DB will be a new RDS instance with a new end point.

Question 15

Encryption at rest is supported for which DBs?

Answer 15

MySQL, Oracle, SQL Server, PostgreSQL, MariaDB

Question 16

How do you perform encryption on DBs?

Answer 16

AWS KMS

Question 17

Will underlying storage, backups, read replicas, and snapshots be encrypted after the RDS instance is encrypted?

Answer 17

Yes

Question 18

Can you encrypt an existing DB instance?

Answer 18

No, you will need to create a new DB instance and migrate your data into it.

Question 19

to scale up RDS

Answer 19

take a snapshot, restore snapshot to larger instance size

Question 20

Multi-AZ is good for

Answer 20

failover/disaster recovery only.

Question 21

If you use Multi-AZ, will AWS handle the replication?

Answer 21

Yes

Question 22

Is Multi-AZ good for improving performance?

Answer 22

No. You need Read Replicas.

Question 23

Use case for Read Replicas

Answer 23

If DB has a lot of reads performed to it, you can change the connection of the EC2 instances to read from read replicas instead of the main DB

Question 24

Multi-AZ db options

Answer 24

All except Aurora, which has it by default.

Question 25

Read replica db options

Answer 25

MySQL Server, PostgreSQL, MariaDB

Question 26

Read replicas are used for

Answer 26

scaling, not DR

Question 27

In order to deploy a read replica

Answer 27

you must have automatic backups turned on

Question 28

How many read replicas can you have for one database?

Answer 28

5

Question 29

Can you have read replicas of read replicas?

Answer 29

Yes, but watch out for latency

Question 30

Is read replica asynchronous or synchronous?

Answer 30

asynchronous

Question 31

Is Multi AZ asynchronous or synchronous?

Answer 31

synchronous

Question 32

Will each read replica have a DNS endpoint?

Answer 32

Yes

Question 33

Can you have read replicas that have multi-AZ turned on?

Answer 33

No. You can create read replicas of Multi-AZ source dbs though.

Question 34

Can read replicas be promoted to their own databases?

Answer 34

Yes, but this breaks replication

Question 35

Can you change the instance size of a read replica?

Answer 35

Yes

Question 36

DynamoDB vs RDS

Answer 36

DynamoDB offers push button scaling, so you can scale your DB on the fly, w/o any down time.
RDS is not so easy and you usually have to use a bigger instance size or add a read replica