Implementing, serving, and using cloud storage
Deep dive IntroductionOrganizations of all types are trying to control costs and satisfy increasingdemands at the same time—demands created by explosive data growth andever-changing requirements. To address these challenges, storage industryprofessionals are turning to cloud computing and cloud storage solutions.
It’s important torecognise that cloud computing is not a new technology, but rather, a newbusiness model that encompasses an existing set of technologies—such as servervirtualization—that reduce the cost of using information technology (IT)resources. Cloud computing takes advantage of Web-based mechanisms that allowscalable, virtualised IT resources to be provided as a service over a network.The advantages of cloud storage and other cloud services include “pay as yougo” (i.e., billing only for services consumed—no fixed costs), the perceptionof infinite capacity (elasticity), and the simplicity of use/management.
When virtualisedstorage is available on demand over a network, organisations are not requiredto buy or provision storage capacity before storing data. As a result,organisations can save a significant amount of money on storage costs becausethey typically only pay for the storage that they actually use.
The Business Case forCloud Storage
Cloud storage meets avariety of demands that applications and end-users normally make. These demandshave traditionally been met in one of two ways: by investing in private diskstorage—directly attached disks or network connected SAN and NAS systems—or bylonger-term retention media, like tape for backup and archiving. Cloud storagepromises a more efficient and flexible alternative for a variety of storage usecases, from Web-based media, such as video, audio, and electronic books; to archiving,where compliance, retention, and e-discovery are simplified. New requirementsare also evolving, such as storage for cloud computing and applications.
To meet these diverserequirements, cloud storage has developed into three major implementations:public, private, and hybrid.
- A publicimplementation is a secure, multi-tenant environment that is externallyavailable to all users.
- A privateimplementation is a secure, single-entity environment, either inside or outsidean organisation’s firewall.
- A hybridimplementation is a combination of public and private clouds.
The term“multi-tenancy” is not new; both have been used to describe applicationarchitectures designed to support multiple users—the “tenants”—for many years.With the advent of cloud computing, this terminology has simply been extendedto include any cloud architecture. Security in a multi-tenancy environment is essential,covers all aspects of the internal and external environment, and extends fromthe application through the server, network, and storage layers.
Equally important tothe cloud storage provider is the allocation of costs. All types of clouds willrequire metering and billing—externally provided clouds that are dedicated to asingle organisation, multi-tenancy clouds, and even internally provided cloudstorage (or at least, cross charging to internal business units).
The challenge for cloudproviders is to show that cloud computing can meet a potential user’s peakdemands without expanding existing facilities and at a price that is less thanor equal to the non-cloud alternative.
The Requirement for aCloud Storage Standard
When the SNIArecognised the significant changes in the way that organisations use storage,it developed the Cloud Data Management Interface (CDMI) standard for cloudstorage vendors and others to use when implementing their own public, hybridand private clouds.
Because the variety ofuse cases rarely share a common interface to cloud storage, SNIA formed atechnical working group (TWG) with over 75 members to develop a standard forcloud storage. In June 2009, it published a use cases and reference model, andin July 2010, the TWG published the first draft standard, the Cloud DataManagement Interface (CDMI). Now, in late 2011, the first draft specificationis ready to be submitted to ISO for certification as an international standard.