Cloud storage is a model of networked online storage where data is stored in 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 can either buy or lease storage capacity from them. 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.
The advantages of Cloud storage are that the customer companies need only pay for the storage they actually use. They do not need to install physical storage devices in their own data-center or offices. Moreover, 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. Finally, the major advantage is that the cloud storage provides users with immediate access to a broad range of resources and applications hosted in the infrastructure of another organization via a web service interface.
Cloud storage architecture
Cloud storage has the same characteristics as cloud computing in terms of agility, scalability, elasticity and multi-tenancy.
Cloud storage is:
- 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 with regard to data replicas
Some examples of cloud storage that are available are:
- Amazon S3
- EMC Atmos
- Google Cloud Storage
- iCloud by Apple
- Windows Azure Storage