EBS Snapshots, restore, and fast snapshot restore

Question 1

What is an EBS snapshot?

Answer 1

It is a way to backup EBS volumes to S3

Question 2

What happens when you take a snapshot of an EBS volume (in terms of resilience)?

Answer 2

The data becomes region resilient as it is stored in S3.

Question 3

How can you migrate data from an EBS volume?

Answer 3

Creating a backup and then restoring the backup

Question 4

Are EBS snapshots incremental or a full copy of the EBS volume?

Answer 4

Snapshots are incremental copies to S3.

Only the first backup is a FULL copy.

Question 5

What is the difference between the first snapshot and the rest?

Answer 5

The first snapshot is a FULL copy.

Question 6

Is the EBS performance affected when taking snapshots of the volume?

Answer 6

No, but it will take time in the background.

Question 7

How do EBS snapshots behave if you delete an incremental snapshot?

Answer 7

It moves data to ensure subsequent snapshots will work properly

Question 8

When creating an EBS volume, when can you expect to have full performance?

Answer 8

Since the creation.

Question 9

What is a lazy restore?

Answer 9

When you restore a volume from a snapshot, you can’t achieve a full performance immediately, this is called lazy restore.
The data is transferred from S3 slowly in the background.

Question 10

What happens when you try to read data that has not been restored yet? (lazy restore related)

Answer 10

When you read data that has not been restored yet, EBS will immediately fetch the data from S3 but you won’t be able to achieve the same level of performance as when you read directly from EBS

Question 11

What is recommended to do when restoring an EBS volume before moving it to production environments?

Answer 11

To read the volume completely with tools like DD (in Linux). It forces the read of all the blocks of the volume so they are available.

Question 12

What does Fast Snapshot Restore (FSR) do?

Answer 12

FSR allows for an immediate restoration.

Question 13

Is there any limit of FSRs per region or AZ?

Answer 13

Yes, you can create 50 FSRs per region.

Question 14

How does Fast Snapshot Restore work?

Answer 14

First, it needs to be enabled on the snapshot.
You pick to which AZ you want to do instant restores.
Each combination of Snapshot and AZ counts as one FSR.

Question 15

What is the disadvantage of FSRs?

Answer 15

FSR is not free and can get expensive with lots of different snapshots - you can get the same result by reading the whole volume with DD.

Question 16

What are Snapshots billed for?

Answer 16

GB/month.

Question 17

How much in GB/month is 20 GB stored for half a month?

Answer 17

10GB/month

Question 18

Are you billed for used data or allocated data (EBS)?

Answer 18

You are billed for the used data, not for the whole EBS volume size.

Question 19

Are you charged more money if you do snapshots of a volume every 5 minutes vs every hour?

Answer 19

The data is incrementally stored which means doing a snapshot every 5 minutes will not necessarily increase the charge as doing it once every hour.