Public cloud storage is often used for backing up data as part of a disaster recovery plan (DRP) as well as archiving email and static non-core application data. Usage is generally charged on a dollar-per-gigabyte-per-month basis, although some service providers may append data transfer and access charges for large enterprise customers.
An advantage of using a public cloud for storage is that the provider is responsible for building and maintaining the storage infrastructure and its associated costs including power, cooling and server maintenance. The customer, who only pays for the resources that are being used, has the ability to scale storage space up or down on demand – in many cases, with just a simple click of the mouse.
A disadvantage of using a public cloud for storage is that the customer turns control of his data over to a service provider. The public storage provider then becomes responsible for maintaining and protecting the data on its multi-tenancy infrastructure and assuring it remains secure during transfer to and from the provider’s facilities. If the provider suffers an outage, the data may not be accessible for the duration and if the provider suffers a catastrophic failure, there is always the risk that the data may be lost.
Another concern with public cloud storage is vendor lock-in due to a lack of standards for cloud storage. If, for example, a company archives its email with Cloud Company XYZ and puts resources into building an application program interface (API) to support this, then it becomes more difficult to switch cloud storage providers should the need arise.