Web Hosting is a commodity, and like everything, it has it's limits. Many hosting companies offer "unlimited" plans, but be aware that there are physical limitations to both disk space, bandwidth, and all other aspects of your hosting service. Before you buy an "unlimited" plan, you need to know what you're getting into.
Firstly, there is no such thing as an unlimited hard drive, everything is determined by the capacity of the drive itself. Furthermore, the network lines that carry data around the web (optic fiber, cable etc) have a finite capacity because there is a limit to the amount of data that can be transferred at any given point in time. So you will never have unlimited diskspace and bandwidth.....because it simply doesn't exist.
And unfortunately, there's a sting in the tail! Because hidden in the provider's terms of service will be very strict limits on CPU, RAM, MySQL, Number of Processes, Concurrent Connections, Disk IO, and Inodes.....and should you try to achieve this mythical "unlimited", you're going to hit those limits very quickly.
What happens then? Normally your account would be suspended for exceeding the limits of the "unlimited plan".
In the case of hitting Inode Limits (number of files) you'll have to delete large amounts of your data to get within the limits of the resources allocated. If you don't want to do that, then you'll be told to upgrade to a virtual private server at a much higher price than what you paid for your mythical unlimited plan.
In the case of hitting CPU and RAM limits then you'll have no other option than to upgrade to the virtual private server as above. So whichever way it goes you're paying more!
Besides these various hidden limits, consider for a moment your neighbours on this "unlimited" server! Possibly a thousand other clients who believe they can use something that doesn't exist. In reality, the server will likely be overloaded with people all trying to get as much for their money as they can, with the end result being that your website loading speed has dropped to a crawl as the CPU and memory hit their limits. And if you have bad neighbours on a server, just like those in real life, you're going to know about it.
Unlimited web hosting plans are simply a marketing ploy to get your business. And the host is taking a gamble that you, and any others on the server, don't attempt to reach the limits of what you've bought. The reality is that most websites only consume a very small amount of bandwidth and disk space, so providers oversell and possibly overload the server with clients to make a profit. Your business is too important to be placed in an environment like that, and there are more sensible and secure options.
WebSpain have always taken the completely opposite approach with the hosting options that we offer to our web design clients as part of our managed service plans:
We run high spec servers populated with a very low number of clients, ensuring maximum CPU and memory availability to everybody.
We use elite datacentres in London and Detroit, which are located on premium business networks.
We offer realistic managed service plans with clearly defined client limits on diskspace, bandwidth, and inodes.
Yes.....it is the old fashioned way, and it's not exactly headline-grabbing marketing material. But we believe in ethical business practices, rather than deliberately misleading unknowing clients (who don't understand the technical aspects) just to get their money.
Please note that our enterprise level hosting resources are only available for our web design clients as a component within our Managed Service Plans.