EBS: Elastic Block Store

Question 1

How resilient is Elastic Block Storage?

Answer 1

EBS is Availability Zone resilient. Data is stored in one AZ.

Question 2

How resilient are Elastic Block Storage snapshots?

Answer 2

EBS snapshots are Region resilient.

Question 3

How is EBS billed?

Answer 3

There is a GB/month fee. There may also be an additional fee for enhanced performance.

Question 4

How can you move an EBS volume that is attached to an EC2 instance in AZ-A to an EC2 instance in AZ-B?

Answer 4

You cannot move the EBS volume to AZ-B. However, you can take a snapshot of the EBS volume, which will be stored in S3. Because S3 is a Region service, you can create a new EBS volume in AZ-B based on the snapshot and then attach the new volume to the EC2 instance in AZ-B.

Question 5

What is the default, general purpose SSD storage provided by EBS?

Answer 5

GP2.

Question 6

What is the volume size range for GP2 and GP3?

Answer 6

1GB - 16TB.

Question 7

What is the size of an IO Credit?

Answer 7

16KB. Since an IOP assumes a 16KB size, this is essentially one IOP.

Question 8

What is the maximum capacity of the EBS IO Credit Bucket for GP2?

Answer 8

5.4M IO Credits.

Question 9

What is the minimum refill rate of the EBS IO Credit Bucket for GP2?

Answer 9

100 IO Credits per second.

Question 10

How much does the Baseline Performance add to the EBS IO Credit Bucket refill rate for GP2?

Answer 10

3 IO Credits per second per GB of volume size.

Question 11

What is the burst rate of the EBS IO Bucket for GP2?

Answer 11

3,000 IOPS

Question 12

At what size volume does the refill rate begin to exceed the burst rate?

Answer 12

1,000 GB

Question 13

What happens when the refill rate of the IO Credit Bucket exceeds the burst rate of GP2 on EBS?

Answer 13

The credit system is no longer used. You always achieve the baseline performance up to a maximum of 16,000 IO Credits per second.

Question 14

Which General Purpose SSD generation uses the Credit Bucket system?

Answer 14

GP2.

Question 15

What is the minimum IOPS and throughput for GP3?

Answer 15

3,000 IOPS and 125 MB/s.

Question 16

What is the maximum IOPS and throughput for GP3?

Answer 16

16,000 IOPS and 1,000 MB/s for an additional cost.

Question 17

When should you use Provisioned IOPS SSD (io1 or io2)?

Answer 17

For consistent low latency.

Question 18

What is the maximum IOPS per volume for io1 and io2?

Answer 18

64,000 IOPS per volume.

Question 19

What is the maximum throughput for io1 and io2?

Answer 19

1,000 MB/s.

Question 20

What is the range of volume sizes for io1 and io2?

Answer 20

4GB-16TB.

Question 21

What is the maximum IOPS/GB that can be provisioned for io1 compared to io2?

Answer 21

50 IOPS/GB for io1.
500 IOPS/GB for io2.

Question 22

Using multiple volumes with a single EC2 instance, what is the maxium performance you can achieve using io1 and io2?

Answer 22

260,000 IOPS and 7,500 MB/s for io1.
160,000 IOPS and 4,750 MB/s for io2.

Question 23

When would you use io1 or io2?

Answer 23

For applications that demand high performance and have latency sensitive workloads.

Question 24

When would you use HDD-based volumes?

Answer 24

Use st1 for throughput optimized, sequential access applications where low cost is more important than high performance. Use for big data, data warehouses, and log processing.

Use sc1 for throughput optimized application where access is infrequent. This is the lowest cost EBS storage type. Use for data requiring fewer scans per day.

Question 25

How do Instance Store volumes compare to EBS volumes in terms of IOPS and throughput?

Answer 25

Instance Store volumes provide many more IOPS and much greater throughput that EBS.

Question 26

What are the cheapest types of EBS storage?

Answer 26

ST1 and SC1

Question 27

Can you boot from ST1 and SC1 EBS volumes?

Answer 27

No.

Question 28

What is the maximum IOPS on GP2/3?

Answer 28

16,000 IOPS.

Question 29

What is the maximum IOPS on IO1/2?

Answer 29

64,000 IOPS.

Question 30

What is the maximum IOPS for a RAID0 set of EBS volumes?

Answer 30

260,000 IOPS because of the limitation on IOPS per EC2 instance.

Question 31

Where are EBS Snapshots stored?

Answer 31

S3, making them Region resilient.

Question 32

What type of backup are EBS Snapshots?

Answer 32

Incremental.

Question 33

What type of restore is used with EBS Snapshots and how can any limitations be overcome?

Answer 33

EBS Snapshots use lazy load restoration. The Fast Snapshot Restore (FSR) feature can enable an immediate restore.

Question 34

How many Fast Snapshot Restores can you enable?

Answer 34

Up to 50 per region. One Snapshot + AZ combo is consider one FSR.

Question 35

How are EBS Snapshots billed?

Answer 35

Per GB/month on used (not allocated data).

Question 36

Can AWS Accounts be set to encrypt EBS data by default?

Answer 36

Yes, using the default KMS Key or a KMS Key you specify.

Question 37

What is the KMS Key used for with regards to encrypted EBS volumes?

Answer 37

The KMS key is used to generate one unique Data Encryption Key (DEK) for a volume. The KMS key is also used to decrypted the DEK when the DEK is need to encrypt/decrypt data.

Question 38

When is a DEK reused in EBS volume encryption?

Answer 38

Only to encrypt Snapshots of a volume and the future volumes created from those Snapshots.

Question 39

How do you remove encryption from an EBS volume?

Answer 39

You cannot remove encryption from an EBS volume.

Question 40

Is the Operating System of an EC2 instance aware of EBS encryption?

Answer 40

No. Encryption is handled between the EC2 host and the volume, meaning there is no performance loss.

Question 41

How many EC2 instances can a GP2 volume be attached to at a time?

Answer 41

One.