Implementing, serving, and using cloud storage

The SNIA's great introduction to cloud storage

Deep dive Introduction Organizations of all types are trying to control costs and satisfy increasing demands at the same time—demands created by explosive data growth and ever-changing requirements. To address these challenges, storage industry professionals are turning to cloud computing and cloud storage solutions.

It’s important to recognise that cloud computing is not a new technology, but rather, a new business model that encompasses an existing set of technologies—such as server virtualization—that reduce the cost of using information technology (IT) resources. Cloud computing takes advantage of Web-based mechanisms that allow scalable, virtualised IT resources to be provided as a service over a network. The advantages of cloud storage and other cloud services include “pay as you go” (i.e., billing only for services consumed—no fixed costs), the perception of infinite capacity (elasticity), and the simplicity of use/management.

When virtualised storage is available on demand over a network, organisations are not required to buy or provision storage capacity before storing data. As a result, organisations can save a significant amount of money on storage costs because they typically only pay for the storage that they actually use.

The Business Case for Cloud Storage

Cloud storage meets a variety of demands that applications and end-users normally make. These demands have traditionally been met in one of two ways: by investing in private disk storage—directly attached disks or network connected SAN and NAS systems—or by longer-term retention media, like tape for backup and archiving. Cloud storage promises a more efficient and flexible alternative for a variety of storage use cases, from Web-based media, such as video, audio, and electronic books; to archiving, where compliance, retention, and e-discovery are simplified. New requirements are also evolving, such as storage for cloud computing and applications.

To meet these diverse requirements, cloud storage has developed into three major implementations: public, private, and hybrid.

- A public implementation is a secure, multi-tenant environment that is externally available to all users.

- A private implementation is a secure, single-entity environment, either inside or outside an organisation’s firewall.

- A hybrid implementation is a combination of public and private clouds.

The term “multi-tenancy” is not new; both have been used to describe application architectures designed to support multiple users—the “tenants”—for many years. With the advent of cloud computing, this terminology has simply been extended to include any cloud architecture. Security in a multi-tenancy environment is essential, covers all aspects of the internal and external environment, and extends from the application through the server, network, and storage layers.

Equally important to the cloud storage provider is the allocation of costs. All types of clouds will require metering and billing—externally provided clouds that are dedicated to a single organisation, multi-tenancy clouds, and even internally provided cloud storage (or at least, cross charging to internal business units).

The challenge for cloud providers is to show that cloud computing can meet a potential user’s peak demands without expanding existing facilities and at a price that is less than or equal to the non-cloud alternative.

The Requirement for a Cloud Storage Standard

When the SNIA recognised the significant changes in the way that organisations use storage, it developed the Cloud Data Management Interface (CDMI) standard for cloud storage vendors and others to use when implementing their own public, hybrid and private clouds.

Because the variety of use cases rarely share a common interface to cloud storage, SNIA formed a technical working group (TWG) with over 75 members to develop a standard for cloud storage. In June 2009, it published a use cases and reference model, and in July 2010, the TWG published the first draft standard, the Cloud Data Management Interface (CDMI). Now, in late 2011, the first draft specification is ready to be submitted to ISO for certification as an international standard.

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