Cloud storage

Cloud storage is a model of networked online storage where data is stored on virtualized pools of storage which are generally hosted by third parties. Hosting companies operate large data centers; and people who require their data to be hosted buy or lease storage capacity from them and use it for their storage needs. The data center operators, in the background, virtualize the resources according to the requirements of the customer and expose them as storage pools, which the customers can themselves use to store files or data objects. Physically, the resource may span across multiple servers.

Cloud storage services may be accessed through a web service application programming interface (API), or through a Web-based user interface.

Cloud storage architecture

Cloud storage has the same characteristics as cloud computing in terms of agility, scalability, elasticity and multi-tenancy. According to ComputerWeekly^[1], it is believed by many experts to have been invented by Joseph Carl Robnett Licklider in the 1960's. Since the sixties, cloud computing has developed along a number of lines, with Web 2.0 being the most recent evolution. However, since the internet only started to offer significant bandwidth in the nineties, cloud computing for the masses has been something of a late developer.

One of the first milestones for cloud computing was the arrival of Salesforce.com in 1999, which pioneered the concept of delivering enterprise applications via a simple website. The services firm paved the way for both specialist and mainstream software firms to deliver applications over the internet. Another notable mention would be FilesAnywhere who also in 1999 helped pioneer cloud based storage services that also enable users to securely share files online. Both of which continue to offer those services still today.

It is difficult to pin down a canonical definition of cloud storage architecture, but object storage is reasonably analogous. Cloud storage services like Amazon S3, cloud storage products like EMC Atmos, and distributed storage research projects like OceanStore^[2] are all examples of object storage and infer the following guidelines.

Cloud storage is:^[2]

• made up of many distributed resources, but still acts as one
• highly fault tolerant through redundancy and distribution of data
• highly durable through the creation of versioned copies
• typically eventually consistent in regards to data replicas

Cloud storage advantages

• Companies need only pay for the storage they actually use as it is also possible for companies by utilizing actual virtual storage features like thin provisioning.^[3]
• Companies do not need to install physical storage devices in their own datacenter or offices, but the fact that storage has to be placed anywhere stays the same (maybe localization costs are lower in offshore locations).^[3]
• Storage maintenance tasks, such as backup, data replication, and purchasing additional storage devices are offloaded to the responsibility of a service provider, allowing organizations to focus on their core business, but the fact stays the same that someone has to pay for the administrative effort for this tasks ^[3]

Potential concerns

See also: Cloud computing security

• Security of stored data and data in transit may be a concern when storing sensitive data at a cloud storage provider ^[3]
• Performance may be lower than local storage depending on how much a customer is willing to spend for WAN bandwidth ^[3]
• Reliability and availability depends on wide area network availability and on the level of precautions taken by the service provider.^{[citation needed]}
• Users with specific records-keeping requirements, such as public agencies that must retain electronic records according to statute, may encounter complications with using cloud computing and storage.^{[citation needed]}

Examples of cloud storage

• Amazon S3
• Windows Azure Storage
• EMC Atmos
• FilesAnywhere
• Google Cloud Storage[5]
• Google App Engine Blobstore
• iCloud by Apple
• OpenStack Swift[6]
• Ubuntu One

See also

• Cloud computing
• Cloud storage gateway
• Comparison of online backup services
• Cloud database

References

1. ^ ComputerWeekly Article: A History of Cloud Computing[1]
2. ^ ^{a b} Sean Rhea, Chris Wells, Patrick Eaton, Dennis Geels, Ben Zhao, Hakim Weatherspoon, and John Kubiatowicz, Maintenance-Free Global Data Storage. IEEE Internet Computing , Vol 5, No 5, September/October 2001, pp 40-49. [2] [3]
3. ^ ^{a b c d e} ZDNet, Nasuni Cloud Storage Gateway By Dan Kusnetzky, June 1, 2010, [4]