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Cloud Storage Use Cases
Today’s storage administrator will almost certainly be getting questions about Cloud based storage.
They might be considering it for their organisations, wondering where it might add value, trying to
understand the myriad of options emerging on the market.
Given that as with many topics related to Cloud there is quite a breadth of services, how is a storage
administrator going to understand the services and options? A good way to start is to know what
Cloud storage is and then what the major use cases are.
What is Cloud storage?
One commentator has stated, “Cloud Storage provides whatever amount of storage you require, on
an immediate basis. It is persistent. It can be accessed in a variety of ways, both in the data centre
where the cloud is housed, as well as via the Internet. If you obtain this from an external provider, it
is purchased on a pay as you go basis. You do not manage it, you use it, and the service provider
manages it.” Here we can see the attributes that define a service as “Cloud”, such as consumption
models, self-service and network access.
Cloud storage is also going to a have number of characteristics which may differentiate it from
existing models. A tolerance for higher network latency, perception of infinite scale, consumption
pricing and access via APIs are good examples. APIs are typically REST based and SNIA has developed
the Cloud Data Management Interface (CDMI) as a standard for API access.
What is not Cloud storage?
One often sees existing storage services that have been given the Cloud label for marketing
purposes. The most prolific examples are managed storage services, which have had a name change
but little change in their service characteristic, all in order to take advantage of the Cloud
bandwagon. Enterprise storage with thin provisioning is not Cloud storage. Also, storage associated
with Cloud Computing or Infrastructure as a Service (IaaS) is not Cloud storage, unless they are
separate services which you are simply integrating.
Typical use cases for Cloud storage are for archive, backup or data access. It is helpful to segment
the styles of services into two segments, User or System based. User based Cloud services are those
that end users interact with directly. The consumer of the service, the person who interacts with it,
configures it and obtains the direct benefit of the service is an end user. There are two popular
services in the user based category, backup or synchronised file services.
Backup services are very popular. Client software is provided and installed onto the device such as
laptop or desktop. These services often provide versioning and encryption. Popular services are
those such as Mozy, Crashplan or Optus Smart Safe.
Synchronised File Services, whilst also being user based, typically solve a different core problem to
backup. These services are for sharing files amongst multiple devices and sometimes multiple users.
They provide convenience at being able to access files in many locations. The most popular service in
this space would be DropBox.
The second segment of Cloud Storage is Systems based. This is where the consumer of the storage is
the storage architect or IT services behind the scene, abstracted away from the direct end users. It’s
the IT staff that are the consumers of the service, interact with it, configure it and obtain the
Again backup services are popular in Systems based Cloud Storage. Many enterprise backup vendors
are adding features to their software to integrate with Cloud storage providers to act as a
destination for backup sets.
A growing area of Systems based Cloud storage is the use of Cloud Storage Gateways (CSGs). CSGs
are virtual or physical appliances which translate more traditional storage protocols such as iSCSI,
NFS or CIFS into cloud storage APIs. This provides a mechanism to provide compatibility with existing
services and requirements, whilst utilising the different characteristics of Cloud storage for the data
As storage administrators consider Cloud storage they can start to segment to the use cases. Is it for
backup for end users or for their backend systems? Is it for file synchronisation services for end
users? Is it as displacement for existing protocols and services via a storage gateway? With different
styles of Cloud storage in the market, it helps to know your use case, along with which services are
and are not Cloud.
REST : Representational State Transfer
A specific set of principles for defining, addressing and interacting with resources addressable by URIs. Architectures that follow these
principles are said to be RESTful. The principles include: abstraction of state into resources and a uniform set of representations and
operations (e.g., HTTP verbs like GET and PUT as the only means to manipulate a resource). RESTful interfaces are contrasted with Web
Services interfaces such as WBEM, which tend to be RPC-like.
API : Application Programming Interface
An interface used by an application program to request services. The term API is usually used to denote interfaces between applications
and the software components that comprise the operating environment (e.g., operating system, file system, volume manager, device
CDMI – Cloud Data Management Interface
A SNIA Architecture standard for Data storage as a Service (DaaS). CDMI is an interface for both the data path and the control path of
cloud storage. CDMI can also be used to manage storage in Cloud Computing deployments.