1.

) Hybrid cloud model

Hybrid Cloud is a mixture of public and private cloud. Non-critical activities are
performed using public cloud while the critical activities are performed using private
cloud. The Hybrid Cloud Model is shown in the diagram below.

Benefits
There are many benefits of deploying cloud as hybrid cloud model. The following
diagram shows some of those benefits:

Scalability
It offers features of both, the public cloud scalability and the private cloud scalability.
Flexibility
It offers secure resources and scalable public resources.

Cost Efficiency
Public clouds are more cost effective than private ones. Therefore, hybrid clouds can
be cost saving.

Security
The private cloud in hybrid cloud ensures higher degree of security.

Disadvantages
Networking Issues
Networking becomes complex due to presence of private and public cloud.

Security Compliance
It is necessary to ensure that cloud services are compliant with security policies of
the organization.

Infrastructure Dependency
The hybrid cloud model is dependent on internal IT infrastructure, therefore it is
necessary to ensure redundancy across data centers.
 2.) What is VM migration (hot (pre copy - post
copy method)/ cold)

Migrating a virtual machine means moving a virtual machine from one host or
datastore to another host or datastore. vSphere supports a couple of VM migration
types that can help you to get better resource utilization across multiple physical
hosts and shift workloads between hosts in order to balance the resource utilization.
The available migration types are:
1. Cold Migration :
A powered down Virtual Machine is carried to separate host or data store.
Virtual Machine’s power state is OFF and there is no need of common
shared storage. There is a lack of CPU check and there is long shortage
time. Log files and configuration files are migrated from the source host to
the destination host.
The first host’s Virtual Machine is shut down and again started on next host.
Applications and OS are terminated on Virtual Machines before moving them
to physical devices. User is given choice of movement of disks associated
from one data store to another one.

2. Hot Migrations :
A powered on Virtual Machine is moved from one physical host to another
physical host. A source host state is cloned to destination host and then that
source host state is discarded. Complete state is shifted to the destination
host. Network is moved to destination Virtual Machine.
A common shared storage is needed and CPU checks are put into use.
Shortage time is very little. Without stoppage of OS or applications, they are
shifted from Virtual Machines to physical machines. The physical server is
freed for maintenance purposes and workloads (which are among physical
servers) are dynamically balanced so as to run at optimized levels.
Downtime of clients is easily avoidable.
Suspend first host’s Virtual Machine and then clone it across registers of
CPU and RAM and again resume some time later on second host. This
migration runs when source system is operative.
 Stage-0:
Is Pre-Migration stage having functional Virtual Machine on primary host.
 Stage-1:
Is Reservation stage initializing container on destination host.
 Stage-2:
Is Iterative pre-copy stage where shadow paging is enabled and all dirty
pages are cloned in succession rounds.
 Stage-3:
Is Stop and copy where first host’s Virtual Machine is suspended and all
remaining Virtual Machine state are synchronized on second host.
 Stage-4:
Is Commitment where there is minimization of Virtual Machine state on
first host.
 Stage-5:
Is Activation stage where second host’s Virtual Machine start and
establishes connection to all local computers resuming all normal
activities.
 3.) What is Virtualisation

Virtualization is the "creation of a virtual (rather than actual) version of something,

such as a server, a desktop, a storage device, an operating system or network
resources".

In other words, Virtualization is a technique, which allows to share a single physical

instance of a resource or an application among multiple customers and organizations.
It does by assigning a logical name to a physical storage and providing a pointer to
that physical resource when demanded.

Types of Virtualization:
1. Hardware Virtualization.
2. Operating system Virtualization.
3. Server Virtualization.
4. Storage Virtualization.

1) Hardware Virtualization:
When the virtual machine software or virtual machine manager (VMM) is directly
installed on the hardware system is known as hardware virtualization.

The main job of hypervisor is to control and monitoring the processor, memory and
other hardware resources.

After virtualization of hardware system we can install different operating system on it

and run different applications on those OS.

Usage:

Hardware virtualization is mainly done for the server platforms, because controlling
virtual machines is much easier than controlling a physical server.

2) Operating System Virtualization:

When the virtual machine software or virtual machine manager (VMM) is installed on
the Host operating system instead of directly on the hardware system is known as
operating system virtualization.

Usage:

Operating System Virtualization is mainly used for testing the applications on different
platforms of OS.

3) Server Virtualization:
When the virtual machine software or virtual machine manager (VMM) is directly
installed on the Server system is known as server virtualization.

Usage:

Server virtualization is done because a single physical server can be divided into
multiple servers on the demand basis and for balancing the load.

4) Storage Virtualization:
Storage virtualization is the process of grouping the physical storage from multiple
network storage devices so that it looks like a single storage device.

Storage virtualization is also implemented by using software applications.

Usage:

Storage virtualization is mainly done for back-up and recovery purposes.

 4.) Virtualisation v/a cloud
.NO Cloud Computing Virtualization

Cloud computing is used to provide While It is used to make various

pools and automated resources that simulated environments through a
1. can be accessed on-demand. physical hardware system.

Cloud computing setup is tedious, While virtualization setup is simple

2. complicated. as compared to cloud computing.

While virtualization is low scalable

3. Cloud computing is high scalable. compared to cloud computing.

While virtualization is less flexible

4. Cloud computing is Very flexible. than cloud computing.

In the condition of disaster recovery,

cloud computing relies on multiple While it relies on single peripheral
5. machines. device.

In cloud computing, the workload is In virtualization, the workload is

6. stateless. stateful.

The total cost of cloud computing is The total cost of virtualization is

7. higher than virtualization. lower than virtualization.

Cloud computing requires many While single dedicated hardware

8. dedicated hardware. can do a great job in it.

While storage space depends on

Cloud computing provides unlimited physical server capacity in
9. storage space. virtualization.

Virtualization is of two types :

Cloud computing is of two types : Hardware virtualization and
10. Public cloud and Private cloud. Application virtualization.
 5.) hypervisor

A hypervisor is a form of virtualization software used in Cloud hosting to

divide and allocate the resources on various pieces of hardware. The
program which provides partitioning, isolation or abstraction is called
virtualization hypervisor. The hypervisor is a hardware virtualization
technique that allows multiple guest operating systems (OS) to run on a
single host system at the same time. A hypervisor is sometimes also called a
virtual machine manager(VMM).

The explanation of a hypervisor up to this point has been fairly simple: it is a layer of
software that sits between the hardware and the one or more virtual machines that it
supports. Its job is also fairly simple. The three characteristics defined by Popek and
Goldberg illustrate these tasks:

 Provide an environment identical to the physical environment

 Provide that environment with minimal performance cost
 Retain complete control of the system resources

6.) Security concerns in CC

Data Loss
Data loss is the most common cloud security risks of cloud computing. It is also known
as data leakage. Data loss is the process in which data is being deleted, corrupted, and
unreadable by a user, software, or application. In a cloud computing environment, data
loss occurs when our sensitive data is somebody else's hands, one or more data
elements can not be utilized by the data owner, hard disk is not working properly, and
software is not updated.

Hacked Interfaces and Insecure APIs

As we all know, cloud computing is completely depends on Internet, so it is compulsory
to protect interfaces and APIs that are used by external users. APIs are the easiest way
to communicate with most of the cloud services. In cloud computing, few services are
available in the public domain. These services can be accessed by third parties, so there
may be a chance that these services easily harmed and hacked by hackers.

Data Breach
Data Breach is the process in which the confidential data is viewed, accessed, or stolen
by the third party without any authorization, so organization's data is hacked by the
hackers.

Vendor lock-in
Vendor lock-in is the of the biggest security risks in cloud computing. Organizations
may face problems when transferring their services from one vendor to another. As
different vendors provide different platforms, that can cause difficulty moving one
cloud to another.

Increased complexity strains IT staff

Migrating, integrating, and operating the cloud services is complex for the IT staff. IT
staff must require the extra capability and skills to manage, integrate, and maintain the
data to the cloud.

Spectre & Meltdown

Spectre & Meltdown allows programs to view and steal data which is currently
processed on computer. It can run on personal computers, mobile devices, and in the
cloud. It can store the password, your personal information such as images, emails,
and business documents in the memory of other running programs.

Denial of Service (DoS) attacks

Denial of service (DoS) attacks occur when the system receives too much traffic to
buffer the server. Mostly, DoS attackers target web servers of large organizations such
as banking sectors, media companies, and government organizations. To recover the
lost data, DoS attackers charge a great deal of time and money to handle the data.

Account hijacking
Account hijacking is a serious security risk in cloud computing. It is the process in which
individual user's or organization's cloud account (bank account, e-mail account, and
social media account) is stolen by hackers. The hackers use the stolen account to
perform unauthorized activities.