Cloud Computing - Mid Sem Solution

Note: We have tried solving the question paper in a very short time span as per our understanding and the study material we had. Feel free to contact us through comment box or through email if you have some descriptive answer.

Q1. Answer the following questions in brief                                   
A. What are the two ways by which public cloud helps the customers to reduce their IT costs?
Answer:

1. Flexible billing models enable customers to pay only for what they use.
2. It reduces the capital expenditures required for setting up the infrastructure.

 Practice Question - What are the components of a cloud computing environment?
 Answer: client, application, platform, infrastructure, server

B. What are the two limitations of SKI Virtualization?
Answer:

1. It is not possible, for instance, to run different versions or even different patch levels of a particular operating system on the same machine. 
2. Whatever versions exist in the host, that same software will be provided in the guest. SKI also sacrifices the security and reliability provided by other virtualization  methods. 

C. A company interested in cloud computing is looking for a service provider who offers a set of basic services such as virtual server provisioning and on-demand storage that can be combined into a platform for deploying and running customized applications. What type of cloud computing model fits these requirements?
Answer: Infrastructure as a Service.

D. How can a software development company leverage the PaaS cloud computing delivery model?
Answer:

Q2. Answer the following questions appropriately.
A. What is 3 - 4 - 5 rule of cloud computing?
Answer: This 3 - 4 - 5 rule stands for:

3 cloud service models
4 deployment models
5 essential characteristics of cloud computing infrastructure

RULE 3 - Cloud service models:
IaaS (Infrastructure as a Service):
The capability provided to the consumer is to provision processing, storage, networks, and other fundamental computing resources where the consumer is able to deploy and run arbitrary software, which can include operating systems and applications.
The consumer does not manage or control the underlying cloud infrastructure but has control over operating systems, storage, deployed applications, and possibly limited control of select networking components (e.g., host firewalls)

PaaS (Platform as a Service):
The capability provided to the consumer is to deploy onto the cloud infrastructure consumer created or acquired applications created using programming languages and tools supported by the provider.
The consumer does not manage or control the underlying cloud infrastructure including network, servers, operating systems, or storage, but has control over the deployed applications and possibly application hosting environment configurations

SaaS(Software as a Service):
The capability provided to the consumer is to use the provider's applications running on a cloud infrastructure. The applications are accessible from various client devices through a thin client interface such as a web browser (e.g., webbased email).
The consumer does not manage or control the underlying cloud infrastructure including network, servers, operating systems, storage, or even individual application capabilities, with the possible exception of limited user specific application configuration settings

RULE 4 - Deployment models:
Private Cloud (Single Org)
The cloud infrastructure is operated solely for a single organization. It may be managed by the
organization or a third party, and may exist on-premises or off-premises, Also called as “Enterprise Cloud”

Community Cloud (Multiple Org)
The cloud infrastructure is shared by several organizations and supports a specific community that has shared concerns (e.g., mission, security requirements, policy, or compliance considerations).
It may be managed by the organizations or a third party and may exist on-premises or off premises.

Public Cloud (For Public)
The cloud infrastructure is made available to the general public or a large industry group and is owned by an organization selling cloud services, Also called as “Internet Cloud”

Hybrid Cloud
The cloud infrastructure is a composition of two or more clouds (private, community, or public)
Leasing public cloud services when private cloud capacity is insufficient, Also called as “Mixed Cloud”

RULE 5 - Characteristics:
On-demand self-service:
Users can provision servers and networks with little human intervention.

Broad network access:
Any computing capabilities are available over the network. Many different devices are allowed access through standardized mechanisms.

Resource pooling:
Multiple users can access clouds that serve other consumers according to demand.
Cloud services need to share resources between users and clients in order to reduce costs.

Elasticity:
Provisioning is rapid and scales out or in based on need.

Metered or measured service:
One of the compelling business use cases for cloud computing is the ability to "pay as you go“, where the consumer pays only for the resources that are actually used by his applications.
Bonus Tips:

Cloud services:

AWS infrastructure Model:

Differences:

Practice - What is OpenStack, Describe shortly.

OpenStack:

• OpenStack is a collection of open source technologies delivering a massively scalable cloud operating system.
• OpenStack cloud operating system controls large pools of compute, storage, and networking resources throughout a data-center, all managed through a dashboard that gives administrators control while empowering their users to provision resources through a web interface.

B. What is Docker, explain in brief ? Describe important commands used for Docker image.
Answer:
Docker:
is an open-source project that automates the deployment of software applications inside containers by providing an additional layer of abstraction and automation of OS-level virtualization on Linux.

In simple words, It's a tool that allows developers, sys-admins etc. to easily deploy their applications in a sandbox (called containers) to run on the host operating system i.e. Linux. The key benefit of Docker is that it allows users to package an application with all of its dependencies into a standardized unit for software development.

Commands for images:

• build - Build an image.
• docker image build -t my_repo/my_image:my_tag .
• Build a Docker image named my_image from the Dockerfile located at the specified path or URL. where -t is short for tag and tells docker to tag the image with the provided tag ,in this case my_tag . 
• The . (period) at the end of the command tells Docker to build the image according to the Dockerfile in the current working directory
• push - Push an image to a remote registry: 
• Once you have an image built you want to push it to a remote registry so it can be shared and pulled down as needed
• ls - List images: 
• docker image ls-List your images. Shows you the size of each image, too.
• history - See intermediate image info: 
• docker image history my_image-Display an image’s intermediate images with sizes and how they were created.
• inspect - 
• See lots of info about an image, including the layers: docker image inspect my_image-Show lots of details about your image, including the layers that make up the image.
• rm - 
• Delete an image: docker image rm my_image - Delete the specified image. If the image is stored in a remote repository, the image will still be available there.
• docker image rm $(docker images -a -q )- Delete all images: 

Note that images that have been pushed to a remote registry will be preserved-that’s one of the benefits of registries.

Below is a  reference diagram for understanding the functioning of Docker 

D. What are the three challenges associated with PaaS?

Answer:

• Since users rely on a provider's infrastructure and software, vendor lock-in can be an issue in PaaS environments.
• If a PaaS provider opts to use a different set of developmental tools, it can again prove to be very disruptive for the user, even resulting in loss of business.
• If a provider stops supporting a certain programming language, users may be forced to change their programming language, or the provider itself. Both are difficult and disruptive steps.

In other words:

Risks of lock-in:

This is one possibility you must check thoroughly before signing up with a provider. If you get locked in a specific language, program, or interface that could affect you with some unnecessary system that you do not require.

Limited Scalability:

PaaS (Platform as a service) can be slightly inflexible when you need supplies on demand. Reducing or expanding based on business needs is limited in a PaaS environment.

Data Backup:

Though PaaS offers backup, you should perform one of your own as the environment can sometimes have the same deficiencies against any disaster.

Q3.
A. What is migration service in the context of virtual machines?
Answer:
The process of moving a running virtual machine or application between different physical machines without disconnecting the client or application, Known as Live migration.

B. What are the two significant differences between the hot migration and cold migration techniques of virtual machines?
Answer:
The migration function is yet another advantage of using virtual machines in Cloud computing systems. There are two types of migration function: hot and cold.

Hot migration

• Hot migration  is the transfer of the OS and applications from virtual machines to physical machines without stopping OS operations or applications.
• In a highly demanding environment such as a public cloud, with even the best servers, the risk of failure starts to rise after around 3 years. 
• Our hot migration function easily avoids downtime caused by failure and maintenance issues with physical machines. 
• Hot migration fulfills several needs:
• Frees up a given physical server for maintenance without downtime for users;
• Dynamically balances workloads among physical servers so that they all run at optimal levels;
• Prevents a facility’s under-performing servers (or those on the brink of failure) from interrupting operations.

Cold migration

• Cold migration, meanwhile, suspends OS and applications on virtual machines before transferring them to physical machines. 
• Types of migration available depend on the hyper-visor selected. With cold migration, you have the option of moving the associated disks from one data store to another.
• The virtual machines are not required to be on shared storage. The virtual machine you want to migrate must be powered off prior to beginning the cold migration process.

C. List down any two scenarios where live migration of virtual machines can be useful?
Answer:
We will not jump directly towards scenarios where live migration of virtual machines is useful, we will first know about what is live migration and how it's useful then move accordingly.

Live migration:
Live migration is the movement of a virtual machine from one physical host to another while continuously powered-up. When properly carried out, this process takes place without any noticeable effect from the point of view of the end user.
Live migration allows an administrator to take a virtual machine off-line for maintenance or upgrading without subjecting the system's users to downtime.

Advantages of Live Migration:
1. Reduce IT costs and improve flexibility with server consolidation.
2. Decrease downtime and improve reliability with business continuity and disaster recovery.
3. Increase energy efficiency by running fewer servers and dynamically powering down unused servers with our green IT solutions
4. Accessing more processing power (in the sense of load balancing)

Scenario 1:
Server 1 Windows Server 2012 R2 and an Intel Xeon E7 processor
Server 4 Windows Server 2016 and an Intel Xeon E7 processor
Live migration from Server 1 to Server 4

Scenario 2:
Server 2 Windows Server 2012 R2 and an Intel i7 processor
Server 3 Windows Server 2016 and an Intel i7 processor
Live migration from Server 2 to Server 3