Cloud storage is a service model in which data is transmitted and stored on remote storage systems, where it is maintained, managed, backed up and made available to users over a network — typically, the internet. Users generally pay for their cloud data storage on a per-consumption, monthly rate.
Cloud storage is based on a virtualized storage infrastructure with accessible interfaces, near-instant elasticity and scalability, multi-tenancy, and metered resources. Cloud-based data is stored in logical pools across disparate, commodity storage servers located on premises or in a data center managed by a third-party cloud provider.
Cloud service providers manage and maintain data transferred to the cloud. Storage services are provided on demand in the cloud, with capacity increasing and decreasing as needed. Organizations opting for cloud storage eliminate the need to buy, manage and maintain in-house storage infrastructure. Cloud storage has radically driven down the per-gigabyte cost of storage, but cloud storage providers have added operating expenses that can make the technology considerably more expensive, depending on how it’s used.
Types Of Cloud Storage
There are three main cloud storage options, based on different access models: public, private and hybrid.
Public Cloud . These storage services provide a multi-tenant storage environment that is most suited for unstructured data on a subscription basis. Data is stored in the service provider’s data centers with storage data spread across multiple regions or continents. Customers generally pay on a per-use basis, similar to the utility payment model. In many cases, there are also transaction charges based on frequency and the volume of data being accessed. This market sector is dominated by the following services:
- Amazon Simple Storage Service (S3) ;
- Amazon Glacier for deep archival or cold storage;
- Google Cloud Storage
- Google Cloud Storage Nearline for cold data; and
- Microsoft Azure
Private Cloud. A private cloud storage service is an in-house storage resource deployed as a dedicated environment protected behind a firewall. Internally hosted private cloud storage implementations emulate some of the features of commercial public cloud services, providing easy access and allocation of storage resources for business users, as well as object storage protocols. Private clouds are appropriate for users who need customization and more control over their data or who have stringent data security or regulatory requirements.
Hybrid Cloud . This cloud storage option is a mix of private cloud storage and third-party public cloud storage services, with a layer of orchestration management to operationally integrate the two platforms.
The model offers businesses flexibility and more data deployment options. An organization might, for example, store actively used and structured data in an on-premises private cloud and unstructured and archival data in a public cloud. A hybrid environment also makes it easier to handle seasonal or unanticipated spikes in data creation or access by cloud bursting to the external storage service and avoiding having to add in-house storage resources.
Adoption of the hybrid cloud model has increased in recent years. Despite the benefits of hybrid clouds, they present technical, business and management challenges. For example, private workloads must access and interact with public cloud storage providers, so compatibility, and reliable and ample network connectivity are important factors. An enterprise-level cloud storage system should be scalable to suit current and future needs, accessible from anywhere and application-agnostic.
How Does Cloud Storage Work
Cloud service providers maintain large data centers in multiple locations around the world. When customers purchase cloud storage from a provider, they turn over most aspects of the data storage to the vendor, including security, capacity, storage servers and computing resources, data availability and delivery over a network. Customer applications can access the stored cloud data through traditional storage protocols or application programming indicators (APIs), or they can also be moved to the cloud.
How cloud storage works varies depending on the type of storage used. The three main types are block storage, file storage and object storage.
- Block storage divides large volumes of data into smaller units called blocks. Each block is associated with a unique identifier and placed on one of the system’s storage drives. Block storage is fast, efficient and provides the low latency required by applications such as databases and high-performance workloads.
- File storage organizes data in a hierarchical system of files and folders; it is commonly used with personal computer storage drives and network-attached storage (NAS). Data in a file storage system is stored in files, and the files are stored in folders. Directories and subdirectories are used to organize the folders and locate files and data. A file storage-based cloud can make data access and retrieval easier, with this hierarchical format being familiar to users and required by some applications.
- Object storage stores data as objects, which consist of three components: data stored in a file, metadata associated with the data file and a unique identifier. Using the REST ful API an object storage protocol stores a file and its associated metadata as a single object and assigns it an identification (ID) number. To retrieve content, the user presents the ID to the system and the content is assembled with all its metadata, authentication and security. Object-based storage systems allow metadata to be customized, which can streamline data access and analysis. With object storage, data can be stored in its native format with massive scalability.
In recent years, object storage vendors have added file system functions and capabilities to their object storage software and hardware largely because object storage was not being adopted fast enough. For example, a cloud storage gateway can provide a file system emulation front end to its object storage; that arrangement often allows applications to access the data without supporting an object storage protocol. All backup applications use the object storage protocol, which is one of the reasons why online backup to a cloud service was the initial successful application for cloud storage.
Most commercial cloud storage services use vast numbers of hard drive storage systems mounted in servers that are linked by a mesh-like network architecture. Service providers have also added high-performance layers to their virtual storage offerings, typically made up of solid-state drives (SSDs). High-performance clouds storage is generally most effective if the servers and applications accessing the storage are also resident in the cloud environment.
Cloud Storage Service Providers
The cloud-based storage market is dominated by Amazon Web Services, Google and Microsoft Azure, but traditional storage vendors like Dell EMC, Hewlett Packard Enterprise, Hitachi Data Systems, IBM and NetApp also operate in the space with products for both enterprise and small business owners that include self service cloud portals to provision and monitor use. Some online file storage services, such as Box and Dropbox, have business-to-consumer (B2C) cloud storage services, as well as business-to-business (B2B) offerings.
Organizations considering the use of cloud storage should be aware of the pros and cons of using cloud in general. If the decision is made to move forward with the cloud, organizations can use topic-based cloud guides to determine which cloud storage types and services best fit their business needs.