Storage as a Service is an essential part of the IaaS and PaaS offerings.  VMs need storage in order to run. There are various types of Cloud StaaS as described in the list below, which makes it possible for end users to access their data from any location, personal computer, tablet, or other device connected to the cloud or Internet. StaaS provides low-cost elastic storage that expands and shrinks based on utilization.

StaaS is distinct from requesting additional storage as an option for an IaaS VM.  Storage as a Service is storage sold as a standalone product. Because this storage is not connected to a specific server or VM, it can be sold and configured in several forms.

It is important to understand that cloud storage is often sold and described in general terms referencing the type of storage being offered.  Examples are object, file, or block storage. The last two are operating system level storage.  Object file is operating system independent.  The underlying storage method (e.g., SAN, network-attached storage [NAS], and direct- attached storage [DAS]); is not disclosed to cloud consumers.

These are the forms of data storage provided by Storage as a Service via the cloud:

Object-based storage

Object-based storage is the most common form of cloud storage. It can be sold and configured as a standalone service offering without a VM. Object storage uses a specialized technique of writing data and metadata used for long-term data storage, archiving, and unique applications that benefit from this technology.

Public cloud providers sell object storage under various marketing brand names, for customers that want backup, archiving, and file storage services. Many popular desktop and server backup and storage applications sold to consumers are just frontend interfaces to object-based storage systems hosted by a cloud provider.

Object-based storage is not a particularly high-performance storage system, but it can handle very large files (or objects) and related metadata, which is actually why it is ideal for a cloud environment. It is optimized for data that is stored once and held indefinitely. It is ideal for use cases and applications for which the network latency is unknown or might be high depending on the end user’s location, device, or network bandwidth. Object storage can maintain the connection and reliability across Internet-based connections.

The cloud provider uses specialized software to present object-based storage features to the cloud consumer, utilizing the underlying SAN, NAS, DAS, or similar form of storage.

Block storage

Block storage requires a host server or VM and is similar to a local hard drive or the default storage included with every VM ordered. You can add the storage to existing VMs or you can add it as independent volumes that the VM OS formats and manages.

Block storage is typically capable of higher performance and is more sensitive to latency. It used as the primary volume for VMs and applications within a datacenter and within the cloud provider. Block storage is also ideal for heavy read/write functionality versus object storage, which is more adept with write once/read many use cases. It is less ideal to map a block-storage volume across the Internet or slower, higher latency network connection.

File storage

File storage is akin to a NAS on-premise. It stores files in a generally accessible shared drive.  File storage is commonly for ‘end users’ and the documents or files they need to perform their jobs.  Cloud providers will provide dedicated File Storage systems under various marketing labels.  File Store systems store the files at the operating system level [as does block storage].  AWS has EFS for example, Azure offers Azure File Storage.  SaaS offerings including O365, Sharepoint, Dropbox, Box, Google Docs and others offer a SaaS platform to manage users file storage needs. 

Pricing

Pricing for storage is usually by the gigabyte (GB) or terabyte (TB) depending on the cloud service provider and the quantity of storage purchased. Because this is a cloud-based offering, providers normally charge only for the amount of data you have utilized rather than pre-allocated amounts. This pay-as-you-use storage model is one of the fundamental characteristics of cloud computing.

Daily backups should be a standard feature of StaaS pricing. The cloud service provider needs to maintain their SLAs as much as you need them to protect your data, so a base level of backup is normally standard and included in the price. The provider might also offer more frequent backups (including real-time data replication) and long-term data retention options.