Data storage is like space, it hates a void. As local storage devices have taken leaps from megabytes to gigabytes and terabytes so has grown our need to fill them with images, movies, and applications.
The current leap we are taking is away from local storage to cloud storage. Loosely defined, "the cloud", is software or hardware resources offered via the internet on a monthly and usage basis. Types of cloud storage solutions range from transactional storage such as Amazons S3 and Microsoft's Azure Storage, to virtual drives like Dropbox and Box.net, and online backup services like Mozy and Veddio.
This migration is evident by the recent news of lower prices for S3 storage from Amazon as a result of explosive growth in usage, reaching 762 billion stored objects in Q4 of 2011 up from 262 billion in 2010.
The official statement from Amazon is that with the explosive usage, their cost is down and therefore those saving are being passed to the customer.
Therein lies one of the key values of cloud storage; with aggregated and shared resources we all benefit from lower costs. As far as scale, local storage mediums still have a way to go before we can tout petabytes of storage on our desktops. Meanwhile Microsoft Azures currently offers virtually unlimited storage capacity. In addition the cloud offers redundancy and mobility.
How does it work?
Physically, cloud services are spanned across multiple processing, memory, and storage resources. These resources are clustered and spanned across multiple locations, which are grouped in "farms" or "zones". To make sure you can send and receive quickly, data is generally cached through your nearest edge location (lower latency). It goes without saying that you need the internet to access or update your cloud stored resources. The more bandwidth the better.
Most IaaS (Infrastructure as a Service) storage options like Amazon S3 and Microsoft Azure Storage are transactional (like working with a database) but there are plenty of software clients and web based services that allow you to interface with your storage objects in a more familiar interaction.
When you get to your PaaS (Platform as a Service) storage offerings like Dropbox and Box.net you start interfacing with desktop software interfaces that integrate with your existing desktop file management (folders and files). Some of these services are backed by the IaaS providers. For example, Dropbox is stored in Amazon's S3, while Box.net uses its own infrastructure (and here's why). Microsoft is also in this space with the consumer facing Sky Drive and so is Apple with the iCloud.
The flavors of service offerings in the SaaS (Software as a Service) space are varied. In this space you can include offerings like Google Docs and Hosted Microsoft SharePoint offerings from various Microsoft Partners or from Microsoft via the Office365 offering. I think Evernote, which I’m using to draft this blog post, fits in this space as well. You can also include the many online storage products from backup companies like Mozy(here is a cool infograph from Mozy on physical storage vs. digital storage) and Carbonite. Backup services generally have their physical storage in-house due to their proprietary security and data compression technologies (and to keep costs down). In the online backup space, you find providers like Veddio that allow you to leverage their infrastructure, platform, and software to create your own Cloud Backup offering.
So how do you use this stuff?
Here is a good reference for getting started with Amazon S3 : http://www.hongkiat.com/blog/amazon-s3-the-beginners-guide/
Microsoft has an entire training kit available for Azure : http://www.microsoft.com/download/en/details.aspx?displaylang=en&id=8396
The first thing you get on Dropbox's site is a getting started video.
Here is a video for new users of Box.net.
Google Docs is easy enough, but here is their help site just in case.
Here are all the resource for deploying and using Hosted SharePoint in the Enterprise.
And in order of appearance :
Learn more about the software strategy behind Amazons Cloud and others at http://highscalability.com/amazon-architecture