Cloud storage is a model of computer data storage in which data, said to be on "the cloud", is stored remotely in logical pools and is accessible to users over a network, typically the Internet. The physical storage spans multiple servers (sometimes in multiple locations), and the physical environment is typically owned and managed by a cloud computing provider. These cloud storage providers are responsible for keeping the data available and accessible, and the physical environment secured, protected, and running. People and organizations buy or lease storage capacity from the providers to store user, organization, or application data.

Cloud storage services may be accessed through a colocated cloud computing service, a web service application programming interface (API) or by applications that use the API, such as cloud desktop storage, a cloud storage gateway or Web-based content management systems.


Cloud computing is believed to have been invented by J. C. R. Licklider in the 1960s with his work on ARPANET to connect people and data from anywhere at any time.[1]

In 1983, CompuServe offered its consumer users a small amount of disk space that could be used to store any files they chose to upload.[2]

In 1994, AT&T launched PersonaLink Services, an online platform for personal and business communication and entrepreneurship. The storage was one of the first to be all web-based, and referenced in their commercials as, "you can think of our electronic meeting place as the cloud."[3] Amazon Web Services introduced their cloud storage service Amazon S3 in 2006, and has gained widespread recognition and adoption as the storage supplier to popular services such as SmugMug, Dropbox, and Pinterest. In 2005, Box announced an online file sharing and personal cloud content management service for businesses.[4]


A high level architecture of cloud storage

Cloud storage is based on highly virtualized infrastructure and is like broader cloud computing in terms of interfaces, near-instant elasticity and scalability, multi-tenancy, and metered resources. Cloud storage services can be used from an off-premises service (Amazon S3) or deployed on-premises (ViON Capacity Services).[5]

There are three types of cloud storage: a hosted object storage service, file storage, and block storage. Each of these cloud storage types offer their own unique advantages.

Examples of object storage services that can be hosted and deployed with cloud storage characteristics include Amazon S3, Oracle Cloud Storage and Microsoft Azure Storage, object storage software like Openstack Swift, object storage systems like EMC Atmos, EMC ECS and Hitachi Content Platform, and distributed storage research projects like OceanStore[6] and VISION Cloud.[7]

Examples of file storage services include Amazon Elastic File System (EFS) and Qumulo Core,[8] used for applications that need access to shared files and require a file system. This storage is often supported with a Network Attached Storage (NAS) server, used for large content repositories, development environments, media stores, or user home directories.

A block storage service like Amazon Elastic Block Store (EBS) is used for other enterprise applications like databases and often require dedicated, low latency storage for each host. This is comparable in certain respects to direct attached storage (DAS) or a storage area network (SAN).

Cloud storage is:[6]


Potential concerns

Data security

Main article: Cloud computing security

Outsourcing data storage increases the attack surface area.[17]

  1. When data has been distributed it is stored at more locations increasing the risk of unauthorized physical access to the data. For example, in cloud based architecture, data is replicated and moved frequently so the risk of unauthorized data recovery increases dramatically. Such as in the case of disposal of old equipment, reuse of drives, reallocation of storage space. The manner that data is replicated depends on the service level a customer chooses and on the service provided. When encryption is in place it can ensure confidentiality. Crypto-shredding can be used when disposing of data (on a disk).
  2. The number of people with access to the data who could be compromised (e.g., bribed, or coerced) increases dramatically. A single company might have a small team of administrators, network engineers, and technicians, but a cloud storage company will have many customers and thousands of servers, therefore a much larger team of technical staff with physical and electronic access to almost all of the data at the entire facility or perhaps the entire company.[18] Decryption keys that are kept by the service user, as opposed to the service provider, limit access to data by service provider employees. As for sharing multiple data in the cloud with multiple users, a large number of keys has to be distributed to users via secure channels for decryption, also it has to be securely stored and managed by the users in their devices. Storing these keys requires rather expensive secure storage. To overcome that, key-aggregate cryptosystem[19] can be used.
  3. It increases the number of networks over which the data travels. Instead of just a local area network (LAN) or storage area network (SAN), data stored on a cloud requires a WAN (wide area network) to connect them both.
  4. By sharing storage and networks with many other users/customers it is possible for other customers to access your data. Sometimes because of erroneous actions, faulty equipment, a bug and sometimes because of criminal intent. This risk applies to all types of storage and not only cloud storage. The risk of having data read during transmission can be mitigated through encryption technology. Encryption in transit protects data as it is being transmitted to and from the cloud service.[20] Encryption at rest protects data that is stored at the service provider. Encrypting data in an on-premises cloud service on-ramp system can provide both kinds of encryption protection.

There are several options available to avoid security issues. One option is to use a private cloud instead of a public cloud. Another option is to ingest data in an encrypted format where the key is held within the on-premise infrastructure. To this end, access is often by use of on-premise cloud storage gateways that have options to encrypt the data prior of transfer.[21]


See also: Financial statement analysis

Companies are not permanent and the services and products they provide can change. Outsourcing data storage to another company needs careful investigation and nothing is ever certain. Contracts set in stone can be worthless when a company ceases to exist or its circumstances change. Companies can:[22][23][24]

  1. Go bankrupt.
  2. Expand and change their focus.
  3. Be purchased by other larger companies.
  4. Be purchased by a company headquartered in or move to a country that negates compliance with export restrictions and thus necessitates a move.
  5. Suffer an irrecoverable disaster.


Other concerns

Hybrid cloud storage

Main article: Hybrid cloud storage

Hybrid cloud storage is a term for a storage infrastructure that uses a combination of on-premises storage resources with cloud storage. The on-premises storage is usually managed by the organization, while the public cloud storage provider is responsible for the management and security of the data stored in the cloud.[33] Hybrid cloud storage can be implemented by an on-premises cloud storage gateway that presents a file system or object storage interface which the users can access in the same way they would access a local storage system. The cloud storage gateway transparently transfers the data to and from the cloud storage service, providing low latency access to the data through a local cache.[21]

Hybrid cloud storage can be used to supplement an organization's internal storage resources, or it can be used as the primary storage infrastructure. In either case, hybrid cloud storage can provide organizations with greater flexibility and scalability than traditional on-premises storage infrastructure.[33]

There are several benefits to using hybrid cloud storage, including the ability to cache frequently used data on-site for quick access, while inactive cold data is stored off-site in the cloud. This can save space, reduce storage costs and improve performance. Additionally, hybrid cloud storage can provide organizations with greater redundancy and fault tolerance, as data is stored in both on-premises and cloud storage infrastructure.[33]

See also


  1. ^ "A History of Cloud Computing". ComputerWeekly.
  2. ^ Louden, Bill (September 1983). "Increase Your 100's Storage with 128K from Compuserve". Portable 100. 1 (1). New England Publications Inc.: 22. ISSN 0738-7016.
  3. ^ Daniela Hernandez (May 23, 2014). "Tech Time Warp of the Week". Wired.
  4. ^ " lets you store, share, work in the computing cloud". Silicon Valley Business Journal. December 16, 2009. Retrieved October 2, 2016.
  5. ^ "On-premises private cloud storage description, characteristics, and options". Archived from the original on 2016-03-22. Retrieved 2012-12-10.
  6. ^ a b S. Rhea, C. Wells, P. Eaton, D. Geels, B. Zhao, H. Weatherspoon, and J. Kubiatowicz, Maintenance-Free Global Data Storage. IEEE Internet Computing, Vol 5, No 5, September/October 2001, pp 40–49. [1] Archived 2012-03-29 at the Wayback Machine [2] Archived 2011-06-23 at the Wayback Machine
  7. ^ Kolodner, Elliot K.; Tal, Sivan; Kyriazis, Dimosthenis; Naor, Dalit; Allalouf, Miriam; Bonelli, Lucia; Brand, Per; Eckert, Albert; Elmroth, Erik; Gogouvitis, Spyridon V.; Harnik, Danny; Hernandez, Francisco; Jaeger, Michael C.; Bayuh Lakew, Ewnetu; Manuel Lopez, Jose; Lorenz, Mirko; Messina, Alberto; Shulman-Peleg, Alexandra; Talyansky, Roman; Voulodimos, Athanasios; Wolfsthal, Yaron (2011). "A Cloud Environment for Data-intensive Storage Services". 2011 IEEE Third International Conference on Cloud Computing Technology and Science. pp. 357–366. CiteSeerX doi:10.1109/CloudCom.2011.55. ISBN 978-1-4673-0090-2. S2CID 96939.
  8. ^ Cardin, Jay. "Qumulo – Because Data Storage Is Not Created Equal". WEI Tech Exchange. WEI. Retrieved 5 August 2021.
  9. ^ Vernik, Gil, et al. "Data On-boarding in Federated Storage Clouds." Proceedings of the 2013 IEEE Sixth International Conference on Cloud Computing. IEEE Computer Society, 2013.
  10. ^ Kemme, Bettina, et al. "Consistency in Distributed Systems (Dagstuhl Seminar 13081)." (2013).
  11. ^ a b c d ZDNet, Nasuni Cloud Storage Gateway By Dan Kusnetzky, June 1, 2010, [3]
  12. ^ Gupta, P (20 October 2013). "The usage and adoption of cloud computing by small and medium businesses". International Journal of Information Management. 33 (5): 861–874. doi:10.1016/j.ijinfomgt.2013.07.001.
  13. ^ "Ochs, R. (2012). The New Decision-Makers. CRN (June 22, 2012). Retrieved on December 10, 2012". Archived from the original on August 5, 2016. Retrieved December 10, 2012.
  14. ^ "4 reasons why cloud and on-premises storage are different, but equally good for people data". 2013-09-09. Archived from the original on 2013-09-25. Retrieved 2013-09-09.
  15. ^ O’Brien, J. A. & Marakas, G. M. (2011). Computer Software. Management Information Systems 10th ed. 145. McGraw-Hill/Irwin
  16. ^ Wu C F, Wang Y S, Liu G N, Amies, A, 2012, Create solutions on IBM SmartCloud Enterprise: Transfer image assets between different accounts IBM developerWorks, June 6.
  17. ^ "The Attack Surface Problem". Archived from the original on 2013-09-21. Retrieved 2013-07-08.
  18. ^ "US-CERT ICS-TIP-12-146-01 Targeted Cyber Intrusion and Detection Mitigation Strategies" (PDF). U.S. Department of Homeland Security. 19 July 2012. Retrieved 5 December 2023.
  19. ^ Chu, Cheng-Kang; Chow, Sherman S.M.; Tzeng, Wen-Guey; Zhou, Jianying; Deng, Robert H. (2014-02-01). "Key-Aggregate Cryptosystem for Scalable Data Sharing in Cloud Storage". IEEE Transactions on Parallel and Distributed Systems. 25 (2): 468–477. doi:10.1109/TPDS.2013.112. ISSN 1045-9219. S2CID 13030328.
  20. ^ "4 Ways: Transfer Files from One OneDrive Account to Another without Downloading". MultCloud. 2023. Retrieved 5 December 2023.
  21. ^ a b Barrett, Mike (July 2014). "Definition: cloud storage gateway". SearchStorage.
  22. ^ Butler, Brandon (2 June 2014). "Cloud's worst-case scenario: What to do if your provider goes belly up". Network World. Retrieved 20 June 2015.
  23. ^ Gaudin, Sharon (12 January 2015). "Verizon gets 'black eye' in long cloud shutdown". Computerworld. Retrieved 20 June 2015.
  24. ^ Butler, Brandon (1 November 2013). "Free cloud storage service MegaCloud goes dark". Network World. Retrieved 20 June 2015.
  25. ^ "Cloud Data Storage Companies, Here are 15 Services and Innovators". 16 September 2022. Retrieved 2022-09-19.
  26. ^ "DoDD 5015.2 DOD Records Management Program, Section 5.1.3" (PDF). Archived from the original (PDF) on March 22, 2011.
  27. ^ Mello, John P. (20 March 2012). "National Security Agency Pressed to Reveal Details on Google Deal". PCWorld. Retrieved 2013-07-08.
  28. ^ Spring, Tom. "Google Ditches Microsoft's Windows Over Security Issues, Report Claims". PCWorld. Archived from the original on 2011-07-01. Retrieved 2013-07-08.
  29. ^ Subashini, S.; Kavitha, V. (2011-01-01). "A survey on security issues in service delivery models of cloud computing". Journal of Network and Computer Applications. 34 (1): 1–11. doi:10.1016/j.jnca.2010.07.006. S2CID 7924866.
  30. ^ Justin Pot (7 December 2011). "Codex Cloud: Upload Your Books & Read Them Online Along With Other People's Uploads". MakeUseOf. Archived from the original on 21 October 2016. Retrieved 12 December 2012.
  31. ^ Nancy Messieh (18 October 2011). "Publishers beware: Is CodexCloud the Grooveshark for ebooks?". NextWeb.
  32. ^ Jones, Hadley (16 January 2014). "When Online File Storage Gets Legal: Regulatory Compliance". CloudWedge. Retrieved 2014-01-16.
  33. ^ a b c Jones, Margaret (July 2019). "Hybrid Cloud Storage". SearchStorage.