L4 - IAAS 2/2

Question 1

What is block virtualization?

Answer 1

Meta data determine mapping of
virtual disk and block number (local in the client systems) to physical disc, block number.
- IO redirection based on the
meta-data

Question 2

Usage of storage virtualization

Answer 2

Flexible mapping
Thin provisioning
Disk expansion and shrinking
Non-disruptive data migration
Improved utilization

Question 3

Is file or block virtualization used more often?

Answer 3

block virtualization is used more often and also performs beter

Question 4

How is block storage accessed?

Answer 4

Though SAN

Question 5

3 Methods of block virtualization implementation

Answer 5

• host based
• storage device based
• network based

Question 6

What is host-based block virtualisation?

Answer 6

• host runs virtualization software
• it maps logical units to physical units

Question 7

What is file virtualization?

Answer 7

• used for NAS
• you have folders and files

Question 8

What are the pros of file virtualization?

Answer 8

• highly scalable
• accessible to multiple runtimes

Question 9

Which file systems are used in file virtualization?

Answer 9

• NTFS, FAT32, UFS

Question 10

What is clustered NAS?

Answer 10

• clustered NAS combines NAS from the same vendor

Question 11

What is DFS?

Answer 11

Distributed file systems
- allows files located on multiple NAS to appear as if on a single NAS
- can combine NASs from different vendors

Question 12

Amazon Block Storage

Answer 12

• block-level storage that can be mounted
• multiple block storage volumes can be combined into a virtual RAID
• snapshots of block storage volume are stored in S3 for backup or replication

Question 13

What is mounting?

Answer 13

When a block-level storage is “mounted,” it means that it is being connected to the operating system so that it can be accessed and used. The process of mounting makes a block-level storage available to the host operating system, allowing it to read and write data to the storage.

Question 14

What is Amazon Instance Storage?

Answer 14

• disks attached to the physical host
• if you stop or terminate an instance, the data on the instance store volumes is lost

Question 15

What is Amazon Elastic File System?

Answer 15

• scalable file storage
• can be mounted to instances
• files can be shared among instances
• file system has to be explicitly created and destroyed

Question 16

Amazon S3

Answer 16

Amazon Simple Storage Service (S3)
- up to 5 TB
- two-level namespaces
- access in Amazon EC2 or from the web

Question 17

Pros and cons of Amazon S3

Answer 17

Pros: reliable and inexpensive storage infrastructure, durable
Cons: slow compared to local disks or EBS, low availability

-> used for backup

Question 18

What are the two-level namespaces for Amazon S3?

Answer 18

In summary, Amazon S3 uses a bucket as the top-level namespace and an object key as the second-level namespace to organize and access data stored in the service.

Question 19

IBM’s differentiation of file and block storage based on use case

Answer 19

Block:
- boot volume
- lowest latency
File:
- mix of structured or unstructured data
- share data with many users at once

Question 20

What is an instance?

Answer 20

running VM that is based on an Amazon Machine Image (AMI)

Question 21

Possible storage options for EC2 Instances?

Answer 21

• boot device volume
• instance store volumes: local discs of the server
• EFS
• EBS

Question 22

Which types of storage are lost when the EC2 instance is terminated?

Answer 22

• boot device volume and instance store volume
• for persistency use EFS and EBS

Question 23

Do you get an elastic IP for EC2 Instances?

Answer 23

Yes, an Elastic IP address is static; it does not change over time. An Elastic IP address is for use in a specific Region only, and cannot be moved to a different Region.

Question 24

What are EBS-backed instances?

Answer 24

are those where the root file system is in the elastic block storage.

Question 25

Is data retained after instance is terminated in EBS-backed instances?

Answer 25

Yes. In Amazon instance store-backed this is not the case.

Question 26

Is there a stopped state for EBS-backed instances?

Answer 26

Yes. Here the root volume is persistent. For Amazon instance store-backed there is no stopped state.

Question 27

what is hibernate?

Answer 27

When the memory content should be saved

Question 28

What is EC2 - VPC?

Answer 28

Virtual private cloud (before there was also EC2 classic)
- your resources are launched into your VPC
- VPC resembles your network in your own data center

Question 29

How can EC2 be accessed?

Answer 29

• primarily through web service API
• interactive tools on top of the API (Amazon Web Services Console, Amazon Command Line tools)
• third-party infrastructure tools (flexera)
• access to server by private or public key pair

Question 30

AWS cloud formation

Answer 30

model your infrastructure
- infrastructure as a code
- specify all resources in a textual way as a json template
- allows standardizing components across your institution
- automatic deployment of resources
- use code editor and versioning tools

Question 31

3 types of pricing

Answer 31

• on-demand pricing
• reserved instances pricing (you reserve an instance for an entire month and save money compared to on-demand pricing)
• pricing spot-market (VM price depends on AWS capacity left)