High Availability

Question 1

You need to provide high availability to RDS. How do you do that?

Answer 1

Build a multi-AZ RDS

Question 2

What happens when the AZ that contains your RDS end point goes down?

Answer 2

RDS will update end point DNS and re-points to other AZ automatically

Question 3

How does RDS multi AZ work?

Answer 3

It maintains two exact copies of your DB in two AZ’s

Question 4

What are the advantages of RDS multi AZ?

Answer 4

high availability

backups and restores are taken from the secondary

Question 5

How do you force a RDS failover?

Answer 5

reboot primary in console or using the rebootinstance API call

Question 6

What are read replicas and what are they used for?

Answer 6

read only copy of DB

Used to scale beyond compute or I/O capacity of a single DB instance by serving read traffic from read only copies

Question 7

How do you create a RDS read replica?

Answer 7

AWS console or CreateDBInstanceReadReplica

Question 8

What RDS instance types support read replicas?

Answer 8

MySQL
postgres
MariaDB
Aurora

Question 9

You’ve created a read replica. While being created users complain of performance issues. Why?

Answer 9

The RDS instance is not multi-az. If it was the read replica would have been created from the secondary instance.

Question 10

How do you connect to read replica?

Answer 10

a new DNS endpoint is created

Question 11

You have an RDS db and wish to create a dev copy. How can you do that?

Answer 11

Create a RR and promote the RR

Question 12

How many read replicas can you have?

Answer 12

5

Question 13

Can you have read replicas in different regions?

Answer 13

Yes

Question 14

What is the key metric for read replicas?

Answer 14

REPLICA LAG

Question 15

How can you tell what RDS version you are using>?

Answer 15

AWS console - details or CLI = aws rds describe-db-instance –region

Question 16

What are the 4 key metrics to monitor for elasticache?

Answer 16

CPU ute
Swap ute
Evictions
Concurrent connections

Question 17

What service should you use if you have performance issue on a read-heavy DB that is infrequently changed?

Answer 17

elasticache

Question 18

What service should you use if you have performance issue on a DB that has many OLAP transactions?

Answer 18

Redshift

Question 19

What are the two types of Aurora?

Answer 19

Aurora

Aurora Serveless

Question 20

How many copies does Aurora maintain of your DB?

Answer 20

2 copies in 3 seperate AZ’s

Question 21

What AWS RDS service is self healing?

Answer 21

Aurora

Question 22

The Aurora CPU utilization is at 100% How do you resolve?

Answer 22

If it is writes causing the issue, scale up the instance size
If it is reads causing the issue, scale out by increasing the number of read replicas

Question 23

You have an Aurora DB and need to ensure encryption at rest is enabled. How do you do that?

Answer 23

Encryption is turned on by default

Question 24

How do you define the read replica fail-over order for Aurora?

Answer 24

Set the tier value

Question 25

Will a new Aurora cluster be created in another region if cross region replication is enabled?

Answer 25

Yes

Question 26

What are some reasons why auto scaling is not working?

Answer 26

Associated key pair does not exist
Sec group does not exist
Autoscaling config is not working
Instance type specified is not supported in the AZ
AZ is no longer supported
Invalid EBS device
Autoscaling service is not enabled on your account
Attempting to attach a service is not enabled on your account
Attempting to attach a EBS block device to an instance - store AMI

Question 27

What are the maximum number of instances per AZ for a spread placement group

Answer 27

7

Question 28

What failover option allows unhealthy instances to be redirected to active instances with minimal downtime?

Answer 28

active active