Nowadays, many hosting companies offer unlimited disk space and unlimited bandwidth in their shared hosting plans. Is it really possible to allocate unlimited disk space and bandwidth on a shared server? Absolutely NOT. If it is really possible then why there are no unlimited disk space and bandwidth plans for VPS hosting or Dedicated server?
Most of the web hosting companies put the restrictions in such a way; you cannot use the more disk space and bandwidth.
How to restrict the Disk space usage:
Almost every hosting companies who are offering unlimited disk space set the restriction on inode usage. An inode is a data structure which contains information about a regular file, folder such as its size and owner. Generally, one file uses one inode. For example, if a web hosting company has set 50000 inode limits that mean you can keep maximum 50000 files/folders in your account. If you have many email accounts or images, you can easily exceed this limit. If your account exceeds their inode limit, your account will be suspended or terminated by them without availability of backup. Also, many web hosting companies put restriction on backup as well. If your account exceeds half of the allocated inode limit, it will be removed from their backup system.
How to restrict the Bandwidth usage:
Any web hosting companies can put the restriction on bandwidth usage using the following ways:
 Restrict total processes per user
It is quite possible to set this limit and if your account exceeds allowed process limit, the visitors will start receiving errors on your web site which is not at all good for your web site and you may lose the traffic.
 Throttle the bandwidth per Virtualhost and set allowed connections per IP address
There are many modules (i.e. mod_cband for Apache etc.) available to throttle the bandwidth usage per Virtualhost. It is also possible to set allowed connection per IP address.
Also, many web hosting companies do not allow large video files as well as flash files.
It is advisable to go through the terms or service before you sign up for such web hosting plans or you can go for limited disk space and bandwidth web hosting plans instead.