CLOUD STROAGE

 PUBLIC CLOUD
 PRIVATE CLOUD
 HYBRID CLOUD

1. Public Cloud:

These storage services provide a multi-tenant storage environment that is most suited
for unstructured data on a subscription basis. Data is stored in the service provider's
data centers with storage data spread across multiple regions or continents. Customers
generally pay on a per-use basis, similar to the utility payment model. In many cases,
there are also transaction charges based on frequency and the volume of data being
accessed. This market sector is dominated by the following services:

 Amazon Simple Storage Service (S3);

 Amazon Glacier for deep archival or cold storage;

 Google Cloud Storage;

 Google Cloud Storage Nearline for cold data; and

 Microsoft Azure.

2. Private Cloud:
A private cloud storage service is an in-house storage resource
deployed as a dedicated environment protected behind a firewall. Internally
hosted private cloud storage implementations emulate some of the features of
commercial public cloud services, providing easy access and allocation of
storage resources for business users, as well as object storage protocols. Private
clouds are appropriate for users who need customization and more control over
their data or who have stringent data security or regulatory requirements.
 3. Hybrid Cloud:
 This cloud storage option is a mix of private cloud storage and
third-party public cloud storage services, with a layer of orchestration
management to operationally integrate the two platforms.

The model offers businesses flexibility and more data deployment options. An
organization might, for example, store actively used and structured data in an on-
premises private cloud and unstructured and archival data in a public cloud. A hybrid
environment also makes it easier to handle seasonal or unanticipated spikes in data
creation or access by cloud bursting to the external storage service and avoiding having
to add in-house storage resources.

Adoption of the hybrid cloud model has increased in recent years. Despite the benefits
of hybrid clouds, they present technical, business and management challenges. For
example, private workloads must access and interact with public cloud storage
providers, so compatibility, and reliable and ample network connectivity are important
factors. An enterprise-level cloud storage system should be scalable to suit current and
future needs, accessible from anywhere and application-agnostic.

 How does cloud storage work?

Cloud service providers maintain large data centers in multiple locations around the
world. When customers purchase cloud storage from a provider, they turn over most
aspects of the data storage to the vendor, including security, capacity, storage servers
and computing resources, data availability and delivery over a network. Customer
applications can access the stored cloud data through traditional storage protocols or
application programming indicators (APIs), or they can also be moved to the cloud.

How cloud storage works varies depending on the type of storage used. The three main
types are block storage, file storage and object storage:
  Block storage:

 Divides large volumes of data into smaller units called blocks. Each block is
associated with a unique identifier and placed on one of the system's storage drives.
Block storage is fast, efficient and provides the low latency required by applications
such as databases and high-performance workloads.

 File storage :

Organizes data in a hierarchical system of files and folders; it is

commonly used with personal computer storage drives and network-attached
storage (NAS). Data in a file storage system is stored in files, and the files are
stored in folders. Directories and subdirectories are used to organize the
folders and locate files and data. A file storage-based cloud can make data
access and retrieval easier, with this hierarchical format being familiar to
users and required by some applications.

 Object storage :

Stores data as objects, which consist of three components: data

stored in a file, metadata associated with the data file and a unique identifier. Using
the RESTful API, an object storage protocol stores a file and its associated
metadata as a single object and assigns it an identification (ID) number. To retrieve
content, the user presents the ID to the system and the content is assembled with all
its metadata, authentication and security. Object-based storage systems allow
metadata to be customized, which can streamline data access and analysis. With
object storage, data can be stored in its native format with massive scalability.

In recent years, object storage vendors have added file system functions and
capabilities to their object storage software and hardware largely because object
storage was not being adopted fast enough. For example, a cloud storage gateway can
provide a file system emulation front end to its object storage; that arrangement often
allows applications to access the data without supporting an object storage protocol. All
backup applications use the object storage protocol, which is one of the reasons
why online backup to a cloud service was the initial successful application for cloud
storage.

Most commercial cloud storage services use vast numbers of hard drive storage
systems mounted in servers that are linked by a mesh-like network architecture. Service
providers have also added high-performance layers to their virtual storage offerings,
typically made up of solid-state drives (SSDs). High-performance clouds storage is
generally most effective if the servers and applications accessing the storage are also
resident in the cloud environment.

 Advantages and disadvantages of cloud storage:

Cloud storage provides many benefits that result in cost
savings and greater convenience for users, compared with a traditional storage area
networks (SAN). There also are shortcomings with cloud storage -- particularly, the
public services -- that make organizations hesitant to use these services or limit how
they use them.

Advantages:

 Pay as you go:

 With a cloud storage service, customers only pay for the storage
they use, eliminating the need for big capital expenses. While cloud storage costs
are recurring, rather than a one-time purchase, they are often so low that, even as
an ongoing expense, they may still be less than the cost of maintaining an in-house
system.

 Utility billing: 

Because customers only pay for the capacity they use, cloud
storage costs can decrease as usage drops. This is in stark contrast to using an in-
house storage system, which will likely be over configured to handle anticipated
growth. A company will pay for more than it needs initially, and the cost of the
storage will never decrease.
 Global availability:

Cloud storage is typically available from any system,

anywhere and at any time; users do not have to worry about operating system
(OS) capability or complex allocation processes.

 Ease of use:

 Cloud storage is easy to access and use, so developers, software

testers and business users can get up and running quickly without having to wait for
an IT (information technology) team to allocate and configure storage resources.

 Off-site security:

  By its very nature, public cloud storage offers a way to move copies of
data to a remote site for backup and security purposes. Again, this represents a
significant cost savings when compared to a company maintaining its own remote
facility.

An in-house cloud storage system can offer some of the above ease-of-use features of
a public cloud service, but it will lack much of the storage capacity flexibility of a public
service. Some hardware vendors are trying to address this issue by allowing their
customers to turn on and off capacity that has already been installed in their arrays.

Disadvantages
 Security:

Data security is the most cited factor that may make companies cautious
about using public cloud storage. The concern is that once data leaves a company's
premises, it no longer has control over how the data is handled and stored. Storing
regulated data is also a concern. Service providers have tried to allay those fears by
enhancing their security capabilities with data encryption, multifactor authentication
(MFA), data storage in multiple locations and improved physical security.
  Data access:

Maintaining access to data stored in the cloud can also be an issue

and could significantly increase the cost of using cloud storage. A company may
need to upgrade its connection to the cloud storage service to handle the volume of
data it expects to transmit. For instance, the monthly cost of an optical link can run
into the thousands of dollars.

 Performance degradation:

A company may run into performance issues if its in-house

applications need to access the data it has stored in the cloud. In those cases, it will
likely require either moving the servers and applications into the same cloud or
bringing the necessary data back in-house.

 Cost: 

If a company requires a lot of cloud storage capacity and frequently moves its
data back and forth between on-premises systems and the cloud, the monthly costs
can be high. Compared to deploying the storage in-house, the ongoing costs could
eventually surpass the cost of implementing and maintaining the on-premises
system.

Cloud storage considerations:

To determine whether using cloud storage will result in operational efficiencies and be cost-
effective, a company must take these four steps:

1. Compare the one-time and recurring costs of purchasing and managing storage capacity in-
house versus the ongoing costs of storing and accessing data in the cloud.

2. Determine if additional telecommunications expenses will be required for the appropriate

access to the service provider.

3. Decide if the cloud storage service provides adequate security and data governance.
4. Develop an in-house cloud security strategy, with procedures for access and use of cloud
storage to maintain effective management of data and control expenses.

Examples of cloud storage:

The most common uses for cloud storage are:

 cloud backup

 disaster recovery (DR)

 archiving infrequently accessed data

 An increasing number of companies are using cloud storage services for DevOps as a way to cut
capital costs. Developers can spin up the compute and storage resources for the duration of the
project development and testing, and then spin them down when it ends.

Increasingly, organizations are moving key applications to the cloud as the service providers
have improved performance and tightened security. In addition, companies that experience
substantial seasonal fluctuations in the volume of data they create can tap into cloud storage to
handle these bursts of data creation activity.

For small to medium-sized businesses (SMBs), some specialized cloud storage services, such as
file sync and share, may be useful on an individual server or user basis. The file syncing features
of these services ensure the versions of files stored locally on the sync client -- a server or end
user's PC -- and in the cloud are consistent. Versioning and file-sharing capabilities also are often
included.

Cloud storage service providers:

The cloud-based storage market is dominated by Amazon Web Services, Google and Microsoft
Azure, but traditional storage vendors like Dell EMC, Hewlett Packard Enterprise, Hitachi Data
Systems, IBM and NetApp also operate in the space with products for both enterprise and small
business owners that include self-service cloud portals to provision and monitor use. Some
online file storage services, such as Box and Dropbox, have business-to-consumer (B2C) cloud
storage services, as well as business-to-business (B2B) offerings.

Organizations considering the use of cloud storage should be aware of the pros and
cons of using cloud computing technologies, in general. If the decision is made to move
forward with the cloud, organizations can use topic-based cloud guides to determine
which cloud storage types and services best fit their business needs.