• Cloud storage means "the storage of data online in the cloud," where in a company data is stored in and accessible from multiple distributed and connected resources that comprise a cloud.
• Cloud Storage is a service that allows to save data on offsite storage system managed by third-party and is made accessible by a web services API.
• Cloud storage can provide the benefits of greater accessibility and reliability; rapid deployment; strong protection for data backup, archival and disaster recovery purposes
• Cloud Storage devices are mainly divided into two categories: Block storage and File storage
• Block storage devices offer raw storage to the clients. This raw storage can be partitioned to create volumes
• File Storage Devices offers storage to clients in form of files, maintaining its own file system. This storage is in the form of Network attached storage (NAS).

Cloud storage Classes

Cloud storage is categorized into two main categories:

Unmanaged Cloud Storage: Here the storage is preconfigured for the consumer. The consumer cannot format nor the consumer can install own file system or change drive properties

Managed Cloud Storage:  It offers online storage space on demand. Managed cloud storage system presents what appears to the user to be a raw disk that the user can partition and format.

Creating cloud storage system:

• The cloud storage system stores multiple copies of data on multiple servers and in multiple locations. If one system fails, then it only requires to change the pointer to stored object's location.
• To aggregate storage assets into cloud storage systems, the cloud provider can use storage virtualization software, Storage GRID.
• It creates a virtualization layer that fetches storage from different storage devices into a single management system
• It can also manage data from CIFS and NFS file system over the Internet
• Virtual storage containers offer high-performance cloud storage systems. Logical Unit Number (LNU) of device, files and other objects are created in virtual storage containers

Issues with Cloud Storage System

Storing the data in the cloud is not that simple task. Apart from its flexibility and convenience, it also has several challenges faced by the consumers. The consumers require the ability to: 

• Know and restrict the physical location of the stored data.
• Provision additional storage on demand.
• Administrator access control over data.
• Have access to a documented process for surely disposing of data storage hardware.
• Verify how data was erased?