• 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.  Also at the vendor level, they are dealing with higher levels of energy so they will be more equipped with managing it in order to keep their own costs down as well.
• 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 (COOP), disaster recovery (DR), security (PII, HIPAA, SARBOX, IA/CND), and records retention laws, regulations, and policies. 
• Storage availability and data protection are 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.

Outsourcing data storage increases the attack surface area. 

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 (i.e. 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 and 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.  Encryption 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 the multiple data with multiple users in the cloud, 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. And 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 (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.  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.

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: 

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.

• 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 depend 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.

• 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 (DISA) to maintain a list of records management products that meet all of the records retention, personally identifiable information (PII), and security (Information Assurance; IA) 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.

• Network file systems
• Outsourcing
• Cloud storage