Chapter 7.2 - Volumes and Snapshots

Question 1

What are Volumes?

Answer 1

It is a virtual hard disk.

You need a minimum of 1 per EC2 instance, which is the Root Device Volume.

This is where the OS is installed.

Question 2

What are Snapshots?

Answer 2

A “photograph” of the virtual disk/volume, which is stored in S3.

Snapshots are a point in time.

Snapshots are incremental.

The first Snapshot may take some time to create as there is no previous point-in-time copy.

Question 3

What are 3 Tips for Snapshots?

Answer 3

Consistent Snapshots

• Snapshots only capture data that has been written to your Amazon EBS volume, which might exclude any data that has been locally cashed by your application or OS.
• For a consistent Snapshot, it is recommended you stop the EC2 instance and take a snap.

Encrypted Snapshots
- If you take a snapshot of an encrypted EBS volume, the snapshot will be encrypted automatically.

Sharing Snapshots (Changing the location of an EC2 instance)

• You can share snapshots, but only in the region in which they were created.
• To share to other regions, you will need copy them to the destination region first.
• How to move EC2 instances from one region to another is a common question on the exam. Using a snapshot is how that is done.

Question 4

What to Know about EBS Volumes?

Answer 4

Location
- EBS volumes will always be in the same AZ as the EC2 it is attached to.

Resizing

• EBS volumes can be resized on the fly.
• They do not need to be stopped and restarted.
• However, you will need to extend the file system in the OS so the OS can see the resized volume.

Volume Type
- EBS volume types can be switched on the fly. You do not need to stop or restart the instance.