Cloud storage

History

Architecture

• Made up of many distributed resources, but still acts as one, either in a federated or a cooperative storage cloud architecture
• 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

  Advantages

• Companies need only pay for the storage they actually use, typically an average of consumption during a month. This does not mean that cloud storage is less expensive, only that it incurs operating expenses rather than capital expenses.
• Businesses using cloud storage can cut their energy consumption by up to 70% making them a more green business.
• Organizations can choose between off-premises and on-premises cloud storage options, or a mixture of the two options, depending on relevant decision criteria that is complementary to initial direct cost savings potential; for instance, continuity of operations, disaster recovery, security, and records retention laws, regulations, and policies.
• Storage availability and data protection is intrinsic to object storage architecture, so depending on the application, the additional technology, effort and cost to add availability and protection can be eliminated.
• Storage maintenance tasks, such as purchasing additional storage capacity, are offloaded to the responsibility of a service provider.
• 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 can be used for copying virtual machine images from the cloud to on-premises locations or to import a virtual machine image from an on-premises location to the cloud image library. In addition, cloud storage can be used to move virtual machine images between user accounts or between data centers.
• Cloud storage can be used as natural disaster proof backup, as normally there are 2 or 3 different backup servers located in different places around the globe.
• Cloud storage can be mapped as a local drive with the WebDAV protocol. It can function as a central file server for organizations with multiple office locations.

  Potential concerns

Data security

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.
2. The number of people with access to the data who could be compromised 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. Decryption keys that are kept by the service user, as opposed to the service provider, limit the 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 can be used.
3. It increases the number of networks over which the data travels. Instead of just a local area network or storage area network, data stored on a cloud requires a WAN 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. 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.

   Longevity

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.

   Accessibility

• Performance for outsourced storage is likely to be lower than local storage, depending on how much a customer is willing to spend for WAN bandwidth
• Reliability and availability depends on wide area network availability and on the level of precautions taken by the service provider. Reliability should be based on hardware as well as various algorithms used.
• Its a given a multiplicity of data storage.

  Other concerns

• Security of stored data and data in transit may be a concern when storing sensitive data at a cloud storage provider
• 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. For instance, the U.S. Department of Defense designated the Defense Information Systems Agency to maintain a list of records management products that meet all of the records retention, personally identifiable information, and security requirements
• Cloud storage is a rich resource for both hackers and national security agencies. Because the cloud holds data from many different users and organizations, hackers see it as a very valuable target.
• Piracy and copyright infringement may be enabled by sites that permit filesharing. For example, the CodexCloud ebook storage site has faced litigation from the owners of the intellectual property uploaded and shared there, as have the GrooveShark and YouTube sites it has been compared to.
• The legal aspect, from a regulatory compliance standpoint, is of concern when storing files domestically and especially internationally.

  Options