Section 7: EC2 Instance Storage

Question 1

What are EBS snapshots?

Answer 1

Make a backup of EBS volume at a point in time, and can copy snapshots across AZ / region

Question 2

How do you change an EBS Volume’s AZ?

Answer 2

1) create snapshot
2) turn snapshot into AMI (Amazon Machine Image)
3) Launch AMI into an EC2 in different AZ / region

Question 3

Can EBS volumes be encrypted? What if taking a snapshot of unencrypted volume? Encrypted volume? What are the encryption statuses for each?

Answer 3

Answer: yes, EBS volumes can be encrypted. Unencrypted volumes have unencrypted snapshots and vice versa. Although you can choose to encrypt a snapshot of an unencrypted EBS.

Question 4

What is an Amazon Machine Image (AMI)?

Answer 4

An AMI is a virtual machine image or a single virtual disk which contains a bootable operating system installed on it. Provides the information requred to launch an EC2 instance.

Question 5

Describe the AMI process for an EC2 Instance

Answer 5

1) start an EC2 and customize it
2) Stop the instance for data integrity
3) build an AMI (this will create EBS snapshots)
4) launch Instances (only works for region that has the AMI)

Question 6

Can you copy an AMI? What are the Details?

Answer 6

Yes, AMI’s can be copied. AMI’s are region specific, but can be moved with snapshots. AWS does not copy launch permissions or other permissions from a source AMI to a new AMI for security.

Question 7

EC2 Instance Store vs EBS Volume. When to use which?

Answer 7

EBS volumes are network drives with good but “limited” performance, if you need high-performance hardware disk, use EC2 Instance Store

Question 8

What are the advantages of an Instance Store over EBS?

Answer 8

• Better I/O performance and higher throughput than EBS volumes
• Good for buffer / cache/ scratch data/ temporary storage
• Multiple instance store volumes can be attached when launching an instance, but no additional ones after launching (unlike EBS)
• For high-performance database that requires an IOPs above 256,000 use instance store

Question 9

What is EFS (Elastic File system?

Answer 9

Elastic file system is a linux based network file system (NFS) that allows you to mount the same file system on EC2 instances that are in different AZs

Question 10

EFS Pro’s and Con’s?

Answer 10

Pro’s:
- EFS can attach to multiple instances
- Highly available, scalable
- encrypted at rest using KMS
- Storage is elastic (grows and shrinks automatically)
Con’s:
- Expensive
- No capacity planning

Question 11

What is EBS multi-attach?

Answer 11

EBS Multi-attach allows you to attach the same EBS volume to multiple EC2 instances in the same AZ
- However it is an ephemeral drive, so we max out I/O for the risk of losing the data on EC2 loss